首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30665篇
  免费   1501篇
  国内免费   173篇
耳鼻咽喉   302篇
儿科学   457篇
妇产科学   356篇
基础医学   4080篇
口腔科学   895篇
临床医学   1962篇
内科学   8234篇
皮肤病学   419篇
神经病学   1840篇
特种医学   1003篇
外科学   4981篇
综合类   151篇
一般理论   1篇
预防医学   974篇
眼科学   592篇
药学   2101篇
中国医学   127篇
肿瘤学   3864篇
  2023年   131篇
  2022年   276篇
  2021年   492篇
  2020年   269篇
  2019年   359篇
  2018年   501篇
  2017年   376篇
  2016年   493篇
  2015年   495篇
  2014年   667篇
  2013年   836篇
  2012年   1298篇
  2011年   1487篇
  2010年   810篇
  2009年   729篇
  2008年   1332篇
  2007年   1473篇
  2006年   1457篇
  2005年   1548篇
  2004年   1501篇
  2003年   1541篇
  2002年   1478篇
  2001年   984篇
  2000年   997篇
  1999年   968篇
  1998年   464篇
  1997年   364篇
  1996年   356篇
  1995年   294篇
  1994年   272篇
  1993年   264篇
  1992年   751篇
  1991年   675篇
  1990年   641篇
  1989年   695篇
  1988年   589篇
  1987年   550篇
  1986年   552篇
  1985年   500篇
  1984年   326篇
  1983年   254篇
  1982年   168篇
  1981年   134篇
  1980年   139篇
  1979年   231篇
  1978年   190篇
  1977年   147篇
  1974年   119篇
  1971年   123篇
  1969年   131篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
1.
Angiotensin II receptor blockers (ARBs) are widely used for the treatment of hypertension. It is believed that treatment with an ARB increases the level of plasma angiotensin II (Ang II) because of a lack of negative feedback on renin activity. However, Ichikawa (Hypertens Res 2001; 24: 641-646) reported that long-term treatment of hypertensive patients with olmesartan resulted in a reduction in plasma Ang II level, though the mechanism was not determined. It has been reported that angiotensin 1-7 (Ang-(1-7)) potentiates the effect of bradykinin and acts as an angiotensin-converting enzyme (ACE) inhibitor. It is known that ACE2, which was discovered as a novel ACE-related carboxypeptidase in 2000, hydrolyzes Ang I to Ang-(1-9) and also Ang II to Ang-(1-7). It has recently been reported that olmesartan increases plasma Ang-(1-7) through an increase in ACE2 expression in rats with myocardial infarction. We hypothesized that over-expression of ACE2 may be related to a reduction in Ang II level and the cardioprotective effect of olmesartan. Administration of 0.5 mg/kg/day of olmesartan for 4 weeks to 12-week-old stroke-prone spontaneously hypertensive rats (SHRSP) significantly reduced blood pressure and left ventricular weight compared to those in SHRSP given a vehicle. Co-administration of olmesartan and (D-Ala7)-Ang-(1-7), a selective Ang-(1-7) antagonist, partially inhibited the effect of olmesartan on blood pressure and left ventricular weight. Interestingly, co-administration of (D-Ala7)-Ang-(1-7) with olmesartan significantly increased the plasma Ang II level (453.2+/-113.8 pg/ml) compared to olmesartan alone (144.9+/-27.0 pg/ml, p<0.05). Moreover, olmesartan significantly increased the cardiac ACE2 expression level compared to that in Wistar Kyoto rats and SHRSP treated with a vehicle. Olmesartan significantly improved cardiovascular remodeling and cardiac nitrite/ nitrate content, but co-administration of olmesartan and (D-Ala7)-Ang-(1-7) partially reversed this anti-remodeling effect and the increase in nitrite/nitrate. These findings suggest that olmesartan may exhibit an ACE inhibitory action in addition to an Ang II receptor blocking action, prevent an increase in Ang II level, and protect cardiovascular remodeling through an increase in cardiac nitric oxide production and endogenous Ang-(1-7) via over-expression of ACE2.  相似文献   
2.
3.
We evaluated the therapeutic efficacy of miconazole (MCZ, Florid-F inj.), a new antifungal agent for parenteral use, in deep-seated fungal infections of respiratory tract system. A daily dose of 400-1,800 mg of MCZ was given intravenously for 12-38 days (mean: 23.4 days) to 7 patients: 2 patients with pulmonary aspergillosis, 1 patient with bronchial aspergillosis, 1 patient with pulmonary candidiasis and 3 patients with candidemia. One additional patient with pulmonary aspergillosis received three instillations of 20 mg of MCZ into the thoracic cavity. The clinical effects were excellent in 1, good in 4 and poor in 3 patients. The efficacy rate was 100% in 5 cases with respiratory fungal infections but 3 cases with candidemia did not respond well to the treatment. Four strains each of Aspergillus sp. and Candida sp. were identified as causative organisms. Seven of the 8 strains were eradicated by administration of MCZ. Side effects observed were irritation and heat in a leg in 1 patient, hyperlipoidemia in 2 patients and eosinophilia in 1 patient. The adverse reactions disappeared after the completion of the therapy. From the above results, we conclude that MCZ is one of the most useful antifungal agents for parenteral use as a first choice on deep-seated fungal infections in the respiratory tract.  相似文献   
4.
Although the human tumor clonogenic assay (HTCA) is extremely reliable in determining clinical correlations, it is a complicated process requiring considerable time in order to obtain results. Thus, an experimental study on cytopathologic observation (cytologic assay) and comparative evaluation between it and HTCA were performed in order to establish a more rapid and accurate drug sensitivity test. Materials included Colon 26, a cell line established in our department, malignant effusion and surgical specimens. In carrying out HTCA according to the Hamburger-Salmon method, the cell suspension samples following exposure to anti-tumor agents (MMC, L-PAM, ADM, CDDP) were cultivated in test tubes for 3-8 hours and stained by the Papanicolaou and Giemsa methods. According to Tokita's criteria, when cellular changes showed as nuclear pyknosis and nuclear destruction were found to have increased significantly in comparison with a control group, the cells were judged to be sensitive. Very similar and parallel results were obtained between HTCA and cytologic assay in this study, with a significant correlation. Cytologic assay was proved to be an easy, rapid and accurate method for testing drug sensitivity and its clinical application can be expected in the future.  相似文献   
5.
Using a 31P-NMR spectroscopy, we monitored the metabolic kinetics of energy organophosphate compound in rat lens during the process of generating galactose cataract. The most remarkable metabolic change in the earlier phase of galactose cataract formation was found in alpha-glycerophosphate. This increased significantly, as compared to controls, since the day 3 of giving feed containing 25% galactose. The high level lasted for up to three weeks, decrease followed by a gradual decrease and subsequently a significant decrease at five weeks. Adenosine triphosphate (ATP) showed a significant decrease in the galactose group compared to the controls from two weeks after beginning of the experiment and the decrease continued. Inorganic orthophosphate increased gradually in the galactose group as compared to the controls, the increase being of significance at one week reading a maximum at two weeks followed by a subsegment decrease. Our basic study suggests that 31P-NMR spectroscopy is a useful technique in lens of the metabolic kinetics, to noninvasively determine the pathophysiology of galactose cataract, which has been studied biochemically and histologically.  相似文献   
6.
PURPOSE: This study evaluated the bone volume, height, and width that can be obtained in alveolar ridge augmentation using titanium mesh and autogenous bone particles in patients with cleft lip/palate. PATIENTS AND METHODS: Subjects were 15 patients with cleft lip/palate requiring tertiary bone graft for implant therapy. Computed tomography (CT) scans were taken before removing the mesh, from 1 to 21 months after bone grafting. Forty-three reconstructed images corresponding to the positions for implant placement were selected for this study. The percent defect filled with bone (%BONE), defined as the percentage of newly formed bone in the space created by the mesh, was measured for image analyses. In linear analyses, 4 parameters were used: increased bone height (IBH), percent increased bone height (%IBH), increased bone width (IBW), and percent increased bone width (%IBW). Factors influencing the quantitative data and the clinical courses of placed implants were also explored. RESULTS: The average %BONE was 91.1%. IBH averaged 4.4 mm, whereas %IBH averaged 88.5%. IBW averaged 4.6 mm, whereas %IBW averaged 86.4%. Little correlation was present between the quantitative data and patient age, or time interval. A significant correlation was identified between the data for span of the grafted area and %BONE (correlation coefficient value = -0.36). However, the diminishing rate was very low. No implants were lost postoperatively. CONCLUSIONS: Alveolar ridge augmentation with titanium mesh and autogenous bone particles from the anterior iliac crest has very high predictability as a preimplant procedure in patients with cleft lip/palate.  相似文献   
7.
Kindling of the visual cortex in cats: comparison with amygdaloid kindling   总被引:3,自引:0,他引:3  
Kindling of the primary visual cortex (VC) was compared with that of the amygdala in cats. VC kindling was basically similar to kindling of the amygdala in that daily electrical stimulation can lead to the development of a generalized convulsion in most subjects, a growth of afterdischarges in their configuration and duration, and a reduction of the afterdischarge threshold. The kindling response of the VC differed from that of the amygdala in a number of respects, i.e., a high afterdischarge threshold, a different pattern of behavioral seizure development, an abrupt growth of electroclinical seizures coincident with the onset of a generalized convulsion, an intersubject variability in seizure susceptibility, and a marked seizure instability. In VC kindling the afterdischarge propagation into the amygdala was not observed until the generalized convulsion developed, and the early involvement of afterdischarge was seen in the pulvinar, lateral geniculate body, and superior colliculus. These data suggest that a neural mechanism different from amygdaloid kindling may participate in VC kindling, and that the subcortical structures of the visual system are involved in the preferential pathway for a seizure generalization from the VC.  相似文献   
8.
Human TNF was detected fairly recently and at present the anti-tumor activity of human recombinant TNF is being examined against various malignant tumors of human origin. In the present study, we report the anti-tumor activity of recombinant human TNF against human malignant glioma cell lines in vitro and in vivo, in addition to its combined effects with HuIFN-beta. The in vitro study was conducted as follows. Thirteen human glioma cell lines were exposed to 100 U/ml TNF, 1,000 IU/ml HuIFN-beta, or both, and the suppression rate was calculated on days 3, 5 and 7. In the in vivo study, nude mice carrying a human glioma cell line, KMS II, in the subcutaneous tissues were divided into groups and drugs were administered intratumorally as described below. 1) control, 2) TNF 5,000 U single administration, 3) TNF 5,000 U, intermittently administered (once/week for two weeks), 4) TNF 5,000 U, continuously administered (3/week for two weeks), 5) HuIFN-beta 50 X 10(4) IU (3/week for two weeks), and 6) combination of 4) with 5). Results of the in vitro study revealed some suppressive effects on proliferation of tumor cells on day 7 in all 13 glioma cell lines examined with 100 U/ml TNF. And also, especially in 8 of 13 cell lines, the suppression rate was more than 30%. The suppressive effects of TNF were augmented by combined use of HuIFN-beta in all cell lines, giving a range of suppression of 67.8 to 99.3%. The in vivo study revealed that the mean tumor weight ratios (control = 100%) on day 19 (the end of the experiment) were as follows; single administration of TNF: 41.3%, intermittent: 46.7%, continuous: 26.7%, HuIFN-beta: 65.9%, combination: 18.5%. Statistical analysis disclosed significant suppressive effects on tumor proliferation between the control group and 3 TNF-administered groups (single, intermittent, and continuous) and that suppression in the continuously administered group was more severe in comparison with the group given single administration. Moreover, it was suggested that combination therapy with TNF and Hu IFN-beta was more effective than a single therapy with TNF only or HuIFN-beta only. From the results described above, it was found that human recombinant TNF had some cytotoxic effects against human malignant gliomas in vitro and in vivo, although the degree of cytotoxicity was not always higher in comparison with the effects of TNF.  相似文献   
9.
Objectives  Porphyromonas gingivalis is one of the microorganisms that most actively produce CH3SH and we have reported that subjects with P . gingivalis have higher CH3SH levels than subjects without P .  gingivalis . However, little is known about the relationship between P . gingivalis levels in saliva and the condition of oral malodor. In this study, we evaluated the association between the relative amount of P . gingivalis in saliva and halitosis in mouth air.
Methods  All of the subjects were patients at the Preventive Dentistry and Breath Odor Clinic of Kyushu Dental College, where they received a periodontal examination. Volatile sulfur compounds (VSC: hydrogen sulfide and methyl mercaptan) were measured using gas chromatography. Saliva samples were collected in a sterile plastic tube over a period of 5 min while the subject chewed on paraffin wax, and were then immediately stored at –80°C until use. Template DNA was obtained from the stored saliva using an Easy-DNA Kit (Invitrogen, CA, USA) according to the manufacturer's instructions. Conventional PCR assays were used to confirm the presence of P . gingivalis . A 5' nuclease TaqMan PCR was used to quantify P . gingivalis in saliva. The relative numbers of bacteria were measured using the comparative threshold cycle method.
Results  We found a quantitative relationship between the P . gingivalis levels in saliva and the condition of halitosis in mouth air.
Conclusion  We analyzed the relationship between the relative amount of P . gingivalis in saliva and oral malodor.  相似文献   
10.
There have only been a few studies on the role of mineral intake in tooth loss. We investigated the association between mineral intake and the prevalence of tooth loss in Japan. We used the baseline data on 1002 pregnant women who were enrolled in the Osaka Maternal and Child Health Study between November 2001 and March 2003. Tooth loss was defined as the previous extraction of one or more teeth. Nutrient intake was assessed by a validated diet history questionnaire. Prevalence odds ratios and confidence intervals were estimated by applying a multiple logistic regression model. The adjusted odds ratio upon comparison of the highest quartile with the lowest quartile of magnesium intake was 0.64 (95% confidence interval, 0.42-0.99), showing a tendency for an inverse dose-response relationship (p for linear trend = 0.05). There were no associations between the level of consumption of calcium, phosphate, iron, zinc, or copper and tooth loss. The present findings suggest that intake of magnesium is related to reduced prevalence of tooth loss among young Japanese women.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号