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   230412篇
  免费   16538篇
  国内免费   5632篇
耳鼻咽喉   3016篇
儿科学   3894篇
妇产科学   4439篇
基础医学   32107篇
口腔科学   4664篇
临床医学   23176篇
内科学   40193篇
皮肤病学   5334篇
神经病学   15396篇
特种医学   11031篇
外国民族医学   21篇
外科学   28789篇
综合类   14186篇
现状与发展   32篇
一般理论   85篇
预防医学   14859篇
眼科学   6459篇
药学   21247篇
  67篇
中国医学   5369篇
肿瘤学   18218篇
  2023年   1898篇
  2022年   4947篇
  2021年   7800篇
  2020年   4730篇
  2019年   5570篇
  2018年   6518篇
  2017年   5257篇
  2016年   6180篇
  2015年   8637篇
  2014年   10772篇
  2013年   12100篇
  2012年   18160篇
  2011年   18246篇
  2010年   11240篇
  2009年   9568篇
  2008年   13603篇
  2007年   13172篇
  2006年   12302篇
  2005年   11487篇
  2004年   9762篇
  2003年   8942篇
  2002年   7661篇
  2001年   6036篇
  2000年   5406篇
  1999年   4490篇
  1998年   2091篇
  1997年   1677篇
  1996年   1554篇
  1995年   1391篇
  1994年   1268篇
  1993年   986篇
  1992年   1945篇
  1991年   1919篇
  1990年   1643篇
  1989年   1505篇
  1988年   1332篇
  1987年   1220篇
  1986年   1154篇
  1985年   977篇
  1984年   699篇
  1983年   603篇
  1982年   440篇
  1981年   408篇
  1980年   369篇
  1979年   537篇
  1978年   415篇
  1977年   391篇
  1976年   347篇
  1974年   366篇
  1973年   338篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function.  相似文献   
62.
63.
小叶锦鸡儿的抗炎作用   总被引:14,自引:0,他引:14  
小叶锦鸡儿可明显对抗角叉菜胶、热烫及巴豆油所致的炎症,抑制小鼠毛细血管通透性、单核巨噬细胞系统的吞噬功能、肉芽组织增生及大鼠炎症部位PGE2的合成和释放。  相似文献   
64.
65.
Twenty-eight patients participated prospectively in a study to evaluate the impact of hysteroscopically detected uterine and cervical anomalies on the success rate of ET in an IVF-ET program. All participants had a normal intrauterine cavity by standard HSG. All the patients had a diagnostic office hysteroscopy under paracervical block before commencing COH. Because our IVF program does not include hysteroscopy as a requirement before undergoing IVF and because the significance of mild intrauterine abnormalities is not yet known, the hysteroscopic findings were not relayed to the personnel involved in the IVF-ET procedure. Sixteen patients (group I) had a normal hysteroscopic evaluation. Twelve patients (group II) had abnormal hysteroscopic findings including small uterine septa, small submucous fibroids, uterine hypoplasia and cervical ridges. Although no difference in patients or cycle characteristics was present, there was a significant difference in the clinical PR between patients in groups I and II. In conclusion, in an IVF-ET program patients with normal hysterography but abnormal hysteroscopic findings had a significantly lower clinical PR, demonstrating the importance of performing hysteroscopy before IVF-ET.  相似文献   
66.
A nephritic condition was developed by infecting Swiss Webster albino mice with the malarial parasite Plasmodium berghei NK 65. These animals were tested for urinary protein and the presence of circulating immune complexes using reagent strips and a polyethylene glycol (PEG) precipitation assay. The circulating immune complexes were isolated from the sera using both affinity chromatography and PEG precipitation and from the kidney by acid elution. The isolated complexes were dissociated into their individual components and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The components of the complexes were transferred to nitrocellulose sheets and probed for the presence of malarial antigens using a rabbit anti-P berghei antisera. The overall humoral response to the malarial parasite was evaluated using a radial immunodiffusion assay. The present study confirmed that the malarial-infected animals not only developed the nephritic condition (as evident by the high levels of proteinuria) but also, as indicated by the PEG assay, have the presence of high levels of circulating immune complexes in their serum. The apparent absence in the SDS gels of any abnormal protein bands followed by the inability of the Western blot to reveal any malarial antigens provides some of the strongest evidence to date that these malarial proteins are not directly involved in the circulating immune complexes believed to be responsible for producing this nephritic condition.  相似文献   
67.
The standard semen analysis frequently fails to identify subfertile males even when findings are normal and conversely often fails to identify fertile males with subnormal semen analyses. This has created the need to produce other tests of sperm physiology that will better distinguish a fertile from a subfertile specimen. Understanding more about the nature of the sperm defect should lead to the establishment of more specific and effective therapies. Until that time, it would still be reasonable to try some of the available empirical therapies even though they may work merely by a placebo mechanism.  相似文献   
68.
Gastrointestinal dysfunction among intensive care unit patients   总被引:3,自引:0,他引:3  
This study used the Acute Physiological and Chronic Health Evaluation (APACHE II) system to select two groups of ICU patients with comparable risk of hospital death to evaluate the importance of GI dysfunction, defined as failure to tolerate enteral nutrition (EN), as a prognostic factor. In our ICU, patients who have not undergone recent bowel surgery are treated by EN. Those patients who cannot tolerate EN are treated by total parenteral nutrition (TPN). One hundred and eleven patients who tolerated EN (functioning gut) and 97 TPN patients who failed to tolerate EN (GI dysfunction) were studied. The mean APACHE II scores of the two groups were 17.7 +/- 6.5 (SD) and 17.7 +/- 5.1, respectively. The observed mortality of patients with GI dysfunction (51%) was significantly higher (p less than .0005) than that of patients with a functioning gut (25%). This was associated with significantly poorer APACHE II mean BP, oxygenation, and creatinine scores among the GI dysfunction patients. Our results suggest that shock, ischemia, and hypoxemia, in addition to causing impairment of renal function, may bring about changes in the GI tract, evident clinically only as a failure to tolerate EN, which have an adverse effect on the prognosis of ICU patients so affected.  相似文献   
69.
SUMMARY: Large simulations have become increasingly complex in many fields, tending to incorporate scale-dependent modeling and algorithms and wide-ranging physical influences. This scale of simulation sophistication has not yet been matched in neuroscience. The authors describe a framework aimed at enabling natural interaction with complex simulations: their configuration, initial conditions, monitoring, and analysis. The architecture is built on three cornerstone components: active probes, adaptive data capture, and visual interface. The resulting synthesis will enable interactive exploration of live simulations running on supercomputing platforms.  相似文献   
70.
There have been a few studies and inconsistent results regarding the coincidence of Parkinson's disease (PD) and atherosclerotic diseases, such as cerebrovascular disease. Carotid intima-media thickness (IMT) is a known marker for subclinical atherosclerosis. The aim of this study was to investigate the carotid IMT between PD patients and controls. We studied 43 patients with PD and 86 matched controls. The carotid IMT in PD patients was significantly smaller than in controls (0.796 +/- 0.179 mm vs. 0.913 +/- 0.237 mm, P < 0.05). In multivariate analysis, the carotid IMT was inversely associated with the duration of levodopa medication and the severity of PD. These results suggest that PD patients have a lower risk of 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