全文获取类型
收费全文 | 500102篇 |
免费 | 33932篇 |
国内免费 | 3007篇 |
专业分类
耳鼻咽喉 | 6287篇 |
儿科学 | 11553篇 |
妇产科学 | 12609篇 |
基础医学 | 72124篇 |
口腔科学 | 15008篇 |
临床医学 | 40385篇 |
内科学 | 102964篇 |
皮肤病学 | 10648篇 |
神经病学 | 39021篇 |
特种医学 | 18906篇 |
外国民族医学 | 91篇 |
外科学 | 75904篇 |
综合类 | 10468篇 |
现状与发展 | 2篇 |
一般理论 | 170篇 |
预防医学 | 31502篇 |
眼科学 | 11357篇 |
药学 | 38149篇 |
1篇 | |
中国医学 | 2421篇 |
肿瘤学 | 37471篇 |
出版年
2021年 | 4487篇 |
2020年 | 3014篇 |
2019年 | 4699篇 |
2018年 | 6985篇 |
2017年 | 5542篇 |
2016年 | 5841篇 |
2015年 | 6582篇 |
2014年 | 9238篇 |
2013年 | 12008篇 |
2012年 | 17178篇 |
2011年 | 17432篇 |
2010年 | 9940篇 |
2009年 | 9760篇 |
2008年 | 15864篇 |
2007年 | 16909篇 |
2006年 | 16579篇 |
2005年 | 15296篇 |
2004年 | 13941篇 |
2003年 | 13406篇 |
2002年 | 12634篇 |
2001年 | 32509篇 |
2000年 | 33002篇 |
1999年 | 27428篇 |
1998年 | 6709篇 |
1997年 | 5524篇 |
1996年 | 5164篇 |
1995年 | 4577篇 |
1994年 | 4122篇 |
1993年 | 3767篇 |
1992年 | 18654篇 |
1991年 | 17151篇 |
1990年 | 16396篇 |
1989年 | 16052篇 |
1988年 | 14485篇 |
1987年 | 13728篇 |
1986年 | 12690篇 |
1985年 | 11837篇 |
1984年 | 8001篇 |
1983年 | 6548篇 |
1982年 | 3231篇 |
1979年 | 6321篇 |
1978年 | 3860篇 |
1977年 | 3395篇 |
1975年 | 2984篇 |
1974年 | 3477篇 |
1973年 | 3267篇 |
1972年 | 3192篇 |
1971年 | 3125篇 |
1970年 | 2783篇 |
1969年 | 2808篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
Elevation of prostaglandins and protein in the aqueous humor is an immediate response to Yag-laser anterior capsulotomy. There was a significant correlation between prostaglandins and thromboxane to the elevation of intraocular pressure. The elevation of protein concentration was proportional to the elevation of prostaglandin F1, but not to thromboxane. The biochemical changes in the aqueous humor were more severe as laser power was increased above 3 mj. While the role of prostaglandins in the elevation of intraocular pressure is uncertain, the present data recommend the selection of laser power below 3 mj to avoid pressure rise instead of inhibition of all prostaglandin synthesis by medication. 相似文献
993.
Y M Chung T S Yeh Y Y Tsai H Chiang J H Liu 《Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift für Augenheilkunde》1988,196(3):161-166
Lymphomatoid granulomatosis is an angiocentric and angiodestructive lympho-proliferative disorder involving multisystems but rarely conjunctiva. We present a 62-year-old Chinese female with lymphomatoid granulomatosis who had an ulcerative conjunctival nodule. Conjunctival biopsy revealed pathological findings important for diagnosis and indicating progression of disease severity. To our knowledge, this is the first report to demonstrate pathological findings characteristic of lymphomatoid granulomatosis with conjunctival involvement. 相似文献
994.
The isolated fourth ventricle (IFV) develops in which obstruction to the out flow of cerebrospinal fluid from the choroid plexus of the fourth ventricle occurs rostrally and caudally. IFV has been a rare occurrence and is difficult to treat. We had an occasion to admit a 28-year-old female to our hospital due to hydrocephalus: she also had a history of meningitis a year ago. The patient was initially managed by a lateral ventriculo-peritoneal shunting procedure. Six months after the procedure the patient began to suffer from vomiting, nausea, and diplopia. CT and MRI scans demonstrated an isolated fourth ventricle enlargement; and thus, a fourth ventriculo-peritoneal shunting procedure was performed under stereotactic conditions. The authors present a case of an isolated fourth ventricle after lateral ventriculo-peritoneal shunting for hydrocephalus, which was treated with a stereotactically guided fourth ventriculo-peritoneal shunting procedure. The technique of this procedure is described below. 相似文献
995.
T E Dolmage T K Waddell F Maltais G H Guyatt T R J Todd S Keshavjee S van Rooy B Krip P LeBlanc R S Goldstein 《The European respiratory journal》2004,23(2):269-274
Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment. 相似文献
996.
The effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on the contractile response of electrically paced guinea pig papillary muscles in vitro were studied. I-65 (0.1-300 mumol/L) decreased the contractile force and inhibited isoprenaline-induced restoration of the contractile response in papillary muscles rendered inexcitable by KCl 22 mmol/L. Both effects were concentration-dependent, and the IC50 were 36.0 and 7.3 mumol/L, respectively. I-65 antagonized the positive inotropic effects of Iso and CaCl2 in a non-competitive manner. Like verapamil, I-65 had a frequency-dependent negative inotropic effect, and delayed the recovery of post-rest potentiation. It is concluded that the negative inotropic effect of I-65 results not only from the reduction of Ca2+-influx through the sarcolemmal membrane, but also from the inhibition of Ca2+ translocation in the sarcoplasmic reticulum. 相似文献
997.
998.
To create a model for studying the regional variation in the histologic structure of left ventricular myocardium and the representativity of samples from endomyocardium in predicting the state of myocardium as a whole, 12 human hearts (3 normal and 9 pathological) were investigated with histoquantitative methods. Ten small endomyocardial areas representing biopsy sites (mean area on section 0.94 mm2) were delineated from each heart. The volume fractions of myocardial fibers (VVMY), interstitial space (VVINT) and connective tissue (VVCT) were determined with a point counting method on these areas. Also the mean fiber diameter was measured. The results were compared with the results from three full thickness samples (mean area 3 cm2) from each heart. The values for fiber diameter estimates were almost identical in endomyocardial samples and full thickness samples. On the other hand, VVCT was significantly higher and VVMY lower in endomyocardial samples. The coefficient of variation (10 endomyocardial areas) was 8.3% for fiber diameter, 17.8% for VVMY and 77.5% for VVCT. When estimates of the regional variation within the heart area are available, it is possible to create a model for the prediction of the number of endomyocardial biopsies needed to reach a given accuracy and probability of measurements. The representativity and clinical value of endomyocardial biopsies are discussed on the basis of this statistical approach. 相似文献
999.
Zhong Rui-kun钟瑞琨 Dong Yong-he董永和and Lu Dao-pei陆道培Institute of Hematology Beijing Medical University Beijing 《中华医学杂志(英文版)》1989,102(7):537-544
In order to understand the mechanism of immunosuppression caused by infusion of placental gamma globulin (PGG) in patients with renal allografts, rheumatoid arthritis, and graft – versus –host disease (GCHD) following bone marrow transplantation (BMT) ,we have examined the effect of PGG in vitro and in a model of the xenogeneic , local graft –ver- sus – host reaction (LGVHR) .PGG inhibited lymphocyte proliferation in mixed lymphocyte cultures (MLC) (P<0.005) and depressed interleukin -2 (IL-2) levels in such cultures at 72 hours (P<0.01) . In contrast phytohemagglutinin (PHA) –and pokeweed mitogen (PWM) –induced T and B lymphocyte blastogenesis was not affected by such PGG treatment .PGG treatment .PGG neither decreased the [3H] TdR pulse incorporation in unstimulated lymphocytes nor affected cell viability .Cell cycle analysis by flow cytometry showed that PGG reduced the percentage of cells in S and G2, M phases during the MLC, but did not alter cell cycling during PWM-stimulated proliferation .
An immunosuppressive effect of PGG on the LGCHR was tested in a model of intracutaneous transplantation of PGG –treat human lymphocytes into cyclophosphamide – immunosuppressed rats. Lymphoprep – separated human tonsillar lymphocytes were incubated with RPMI-1640 buffer containing:(1)PGG,4mg/ml,(2) human plasma albumin,4mg/ml,(3)mitomycin-C,25ug/ml, or (4) no additive. Cell of each preparation (3x107cells in 0.1ml) were injected intracutaneously into cyclophosphamide-treated male rats at separate abdominal locations. A fifth site received only the buffer solution. Five days after injection of cells ,each rat received [125 I]IUdR (10uCi) intraperitoneally and was killed after 5 hours. For each site of injection, the diameters of induration were measured and 125 I was counted . There was no difference between buffer – treated and a ibumin – treated groups either in the diameter of the area of induration (t=0.66;P>0.5)or in radioactive counts(t=0.22;P>0.05).In the PGG –treated group, the induration and radioactivity measurements were significantly less than in control groups (t=3.72 and P<0.1;t=2.62 and P<0.02,respectively ) Cytophilic antibodies in PGG were thought to inhibit an early phase of T cell activation, and not to be cytotoxicity .In the LGVHR, the immune response might be abrogated either by immuno- regulatory suppression of T cell function or by toxicity to the infused lymphoid cells. For some clinical purposes, immuno- modulating, human antibodies might be preferred to murine, monoclonal antibodies. 相似文献
1000.
Induction of gastric tumor and intestinal metaplasia in rats exposed to localized X-irradiation of the gastric region 总被引:2,自引:0,他引:2
The induction of gastric tumor and intestinal metaplasia was examined in 8-week-old male JCL/SD rats exposed to localized X-irradiation of the gastric region. The animals were each given two 20 Gy fractions of X-rays, with a one-week interval between fractions (total, 40 Gy). Nine atypical hyperplasias (20%) and 13 adenocarcinomas (28%) in the pyloric mucosa of the glandular stomach were found in 46 animals with X-irradiation. The incidence of intestinal metaplasia was 93% in the pyloric mucosa, 50% in the fundic mucosa and 96% in both the pyloric and fundic mucosa. Type B metaplasia (intestinal metaplasia without Paneth cells) was most common and type C (intestinal metaplasia with Paneth cells) was less frequent. No gastric tumor or intestinal metaplasia appeared in non-irradiated control rats. This study shows that local X-irradiation of the gastric region induced both gastric tumor and intestinal metaplasia independently. 相似文献