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   5663篇
  免费   313篇
  国内免费   23篇
耳鼻咽喉   66篇
儿科学   114篇
妇产科学   32篇
基础医学   583篇
口腔科学   97篇
临床医学   357篇
内科学   1673篇
皮肤病学   246篇
神经病学   283篇
特种医学   169篇
外科学   1040篇
综合类   38篇
预防医学   142篇
眼科学   80篇
药学   365篇
中国医学   6篇
肿瘤学   708篇
  2023年   56篇
  2022年   120篇
  2021年   186篇
  2020年   102篇
  2019年   123篇
  2018年   128篇
  2017年   97篇
  2016年   116篇
  2015年   142篇
  2014年   139篇
  2013年   186篇
  2012年   282篇
  2011年   277篇
  2010年   148篇
  2009年   143篇
  2008年   215篇
  2007年   182篇
  2006年   207篇
  2005年   210篇
  2004年   224篇
  2003年   224篇
  2002年   216篇
  2001年   188篇
  2000年   212篇
  1999年   162篇
  1998年   76篇
  1997年   63篇
  1996年   53篇
  1995年   57篇
  1994年   60篇
  1993年   44篇
  1992年   102篇
  1991年   110篇
  1990年   95篇
  1989年   111篇
  1988年   99篇
  1987年   85篇
  1986年   113篇
  1985年   88篇
  1984年   53篇
  1983年   58篇
  1982年   31篇
  1979年   40篇
  1978年   22篇
  1977年   44篇
  1975年   28篇
  1972年   30篇
  1971年   32篇
  1970年   32篇
  1969年   25篇
排序方式: 共有5999条查询结果,搜索用时 0 毫秒
11.
We have applied DNA flow cytometric analysis to paraffin-embedded tissue sections of primary malignant melanomas. Conventionally, flow cytometric analysis of paraffin-embedded tissue sections has been done by the method of Hedley et al. We added ultrasound treatment to the method of Hedley et al. and a lower value of coefficient of variation was shown. Furthermore, a new technique, fluorescence in situ hybridization with a chromosome-specific repetitive DNA probe, was used for the analysis of chromosomal numerical aberrations in the same paraffin-embedded tissue sections. The DNA flow cytometric analysis showed that in 8 cases six primary malignant melanomas were of the aneuploid pattern and two cases of lentigo maligna (melamona in situ) were of the diploid pattern. By fluorescence in situ hybridization, the two cases with the diploid pattern had spots/nucleus of 1.28 and 1.12, and those with the aneuploid pattern had spots/nucleus from 2.01 to 2.27. Only one nodular melanoma in an aneuploid case showed spots/nucleus of 1.71. These data indicate that fluorescence in situ hybridization with chromosome-specific repetitive DNA probes can serve as a cytogenetic tool for the analysis of interphase nuclei of solid human tumors and may be useful for the study of tumor cell heterogeneity.  相似文献   
12.
Time density curve (TDC) can be reconstructed from the data of intravenous digital subtraction angiography (IVDSA). We evaluated peak time (PT) and modal transit time (MOTT) of the TDC as the probable indicator of cerebral intravascular blood flow. Cerebral IVDSA and single photon emission CT (SPECT) were performed on 12 patients of ischemic cerebrovascular disease, which consisted of 3 internal carotid artery (ICA) occlusions, one middle cerebral artery (MCA) occlusion, one anterior cerebral artery (ACA) branch occlusion and 7 lacunar infarctions. We classified former 4 patients as occlusion group and latter 8 as reference group. In 3 patients (2 ICA and one MCA occlusions), SPECT study revealed definite hypoaccumulation in the MCA territory of occlusive side. Two regions of interest (ROI) were placed on the territories of right and left middle cerebral arteries in the frontal view of cerebral IVDSA. Digital data processor fitted gamma curve to the TDC of each ROI, and calculated PT and MOTT. The absolute lateralities of PT and MOTT of MCA territory was significantly (p less than 0.05) larger in occlusion group than reference group. Patients with hypoaccumulation in SPECT had significantly (p less than 0.02) larger laterality of MOTT than patients with isoaccumulation. One ICA occluded patient without hypoaccumulation in corresponding MCA territory had relatively small laterality of MOTT similar to the patients of ACA branch occlusion and lacunar infarction. These results suggest that PT and MOTT are possible to detect the laterality of the intravascular blood flow in MCA territories caused by major artery occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
13.
Kampo, a Japanese-Chinese traditional herbal medicine, has been used for the treatment of various diseases for about 3,000 years in China. Among herbal medicines, Sairei-to is well known for improving the symptoms of rheumatoid arthritis (RA) and other collagen diseases. However, its immunosuppressive effects on autoimmune cutaneous phenomena are not completely understood. We investigated the effects of Sairei-to on the development of lupus dermatoses in autoimmune-prone MRL/Mp-lpr/lpr (MRL/lpr) mice, an animal model which spontaneously develops skin lesions similar to those seen in human lupus erythematosus. Virgin female MRL/lpr mice at 1 month of age, which were treated orally with Sairei-to, had reduced amounts of IgG deposition at the dermoepidermal junction, titers of anti-DNA antibodies and rheumatoid factor, and lymphoproliferation. These results support the use of traditional herbal medicines in patients with human RA and systemic lupus erythematosus.  相似文献   
14.
We reported a 57-year-old female patient recently suffering from frequent seizures such as motionless staring and oral automatism. Electroencephalograms showed spikes in the right sphenoidal derivation and magnetic resonance images revealed an abnormal region, most likely related with a migration disorder such as a focal cortical dysplasia. She was diagnosed as mesiotemporal lobe epilepsy associated with a migration disorder. Seizure disappeared after medication therapy was done. No previous literature has described such a case, thus this is the first report of an epilepsy associated with migration disorder newly onset in a patient older than 50 years old.  相似文献   
15.
Tissue factor in neutrophils: yes   总被引:4,自引:1,他引:3  
  相似文献   
16.
Histamine (HA) is the most important mediator of nasal allergy and nasal hypersensitivity. To investigate HA metabolism, HA content and activities of its synthetic enzyme, histidine decarboxylase (HDC) and degrading enzymes, histamine-N-methyltransferase (HMT) and diamine oxidase (DAO) in nasal mucosa of human and toluene diisocyanate (TDI) sensitized guinea-pigs were measured. In human nasal mucosa and nasal polyps, HA content and HDC activity were 80-200 nmol/g tissue, 20-30 fmol/min/mg protein respectively. Among two degrading enzymes, HMT activity was 20-200 times higher than that of DAO. In the nasal mucosa of guinea-pigs, HA content was significantly increased by TDI sensitization, and was decreased immediately after TDI provocation. In 24 hours after provocation, HA content recovered to 80% of pre-provocation level. HDC activity increased by TDI sensitization significantly. Though HMT activity increased slightly by TDI sensitization and provocation, DAO activity was unchanged. The data suggest that, increase in turnover rate of HA is present in allergic nasal mucosa.  相似文献   
17.
Purpose: We examined whether bone marrow-derived dendritic cells (DCs) could induce antitumor immunity when a chemotherapeutic drug was added. Methods: CT26 (a murine colon cancer cell line syngeneic with BALB/c) and CT26-bearing mice were treated with mitomycin C (MMC) intraperitoneally (i.p.). Next, mice immunized with a coinjection of DCs and MMC-treated CT26 (i.p.) were given an intradermal inoculation of CT26. Finally, CT26-bearing mice were treated with MMC (i.p.) with or without DCs, given peritumorally. Results: Although the inoculated tumor was not rejected in the control mice, CT26 was rejected in 50% of the mice injected with MMC alone. Apoptosis was observed in the MMC-treated CT26 cells in vitro and in vivo. Immunization with DCs and apoptotic CT26 cells, but not with apoptotic CT26 alone, gave protection against tumor challenge in 7 of 13 mice. A significantly higher level of cytotoxic T-cell activity and interferon-γ production was seen in the protected mice. When MMC (i.p.) treatment was followed by peritumoral DC injection in the CT26-bearing mice, remarkable therapeutic effects were observed. Conclusion: DCs can collaborate with chemotherapy-induced apoptotic tumor cells and elicit improved antitumor immunity, probably through the acquisition of tumor-associated antigens from apoptotic tumor cells. Received: January 7, 2002 / Accepted: September 3, 2002 Acknowledgments. We thank Dr. Kazuo Kinoshita for his useful advice on using flow cytometry. This research was partly supported by the Ministry of Education, Culture, Sports, Science and Technology (No. 11671160). Reprint requests to: S. Yamasaki  相似文献   
18.
The binding of twelve structurally related sulfonamides to serum albumins including human was investigated using a circular dichroic technique. Some differences of circular dichroic spectral characteristics were observed when sulfonamides were bound to the same albumin or when the drug was bound to several albumins. The differences in these circular dichroic characteristics may be due to various asymmetries. The Scatchard plots indicated that only the primary site was capable of inducing ellipticities of the drugs. The interaction with rabbit serum albumin showed significantly large binding constants and apparent anisotropy factors (g′, values), in comparison with other albumins. No significant correlation between the g′ values of the induced circular dichroic bands and partition coefficients or/and pKa values was observed. The induced ellipticities of the drug-albumin complexes decreased with pH. This pH dependence can be explained by the ionization of drug and albumin as well as the conformational change of the albumin.  相似文献   
19.
20.
The localization of fibrinogen and low-density lipoprotein (LDL) in the arterial wall has been studied to determine whether they mediate the effects of hypertension and/or hypercholesteraemia on atherogenesis. In untreated control rabbits, fibrinogen was localized in the caveolae and vesicles of the endothelial cells and in the subendothelial spaces of the aorta. No fibrinogen was found in the subendothelial spaces of the cerebral artery. Hypertension or hypercholesteraemia was accompanied by enhanced insudation of fibrinogen into the subendothelial spaces of the aorta and cerebral artery, and fibrinogen deposition was most prominent in the hypercholesteraemic rabbits with induced renovascular hypertension. The insudation of fibrinogen appeared to occur by way of vesicular transport, and to some extent by junctional transport. In the untreated control rabbits, LDL was localized only in the caveolae and vesicles of endothelial cells in both aorta and cerebral artery. LDL was deposited in the subendothelial space of the aorta of hypercholesteraemic rabbits with or without hypertension, and in the cerebral artery of hypercholesteraemic rabbits with hypertension. These findings suggest that fibrinogen insudates into the intima of the aorta and cerebral artery both during hypertension and hypercholesteraemia, and that LDL insudation into the intima of the aorta in hypercholesteraemia is accentuated by hypertension. LDL insudated into the intima of the cerebral artery in the presence of hypercholesteraemia linked to hypertension. Thus, hypertension plays a significant role in the pathogenesis of cerebral atherosclerosis.  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