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   1925篇
  免费   159篇
  国内免费   30篇
耳鼻咽喉   22篇
儿科学   86篇
妇产科学   34篇
基础医学   220篇
口腔科学   89篇
临床医学   191篇
内科学   336篇
皮肤病学   21篇
神经病学   167篇
特种医学   294篇
外科学   170篇
综合类   42篇
预防医学   181篇
眼科学   56篇
药学   140篇
肿瘤学   65篇
  2021年   25篇
  2020年   12篇
  2019年   21篇
  2018年   31篇
  2017年   17篇
  2016年   19篇
  2015年   31篇
  2014年   48篇
  2013年   37篇
  2012年   48篇
  2011年   72篇
  2010年   59篇
  2009年   44篇
  2008年   52篇
  2007年   59篇
  2006年   73篇
  2005年   61篇
  2004年   47篇
  2003年   53篇
  2002年   48篇
  2001年   41篇
  2000年   47篇
  1999年   38篇
  1998年   72篇
  1997年   81篇
  1996年   93篇
  1995年   54篇
  1994年   47篇
  1993年   47篇
  1992年   46篇
  1991年   33篇
  1990年   44篇
  1989年   59篇
  1988年   62篇
  1987年   53篇
  1986年   49篇
  1985年   57篇
  1984年   26篇
  1983年   21篇
  1982年   26篇
  1981年   19篇
  1980年   18篇
  1979年   19篇
  1978年   10篇
  1977年   24篇
  1976年   20篇
  1975年   10篇
  1973年   11篇
  1969年   10篇
  1968年   10篇
排序方式: 共有2114条查询结果,搜索用时 0 毫秒
1.
2.
Sonoelasticity imaging of prostate cancer: in vitro results   总被引:2,自引:0,他引:2  
  相似文献   
3.
4.
In 1995, the National League for Nursing commissioned a Panel on Interdisciplinary/Transdisciplinary Education. The focus of the Panel's work was to examine educational issues that transcend the health professions and to make recommendations for future implementation of an interdisciplinary approach to addressing them. This article is being simultaneously published by several professional journals. The goal is to seek as much feedback as possible.  相似文献   
5.
Analysis of the DNA content of various solid tumors and hematological malignancies may provide useful prognostic information. To date, however, there has been a striking lack of correlation between DNA content in neoplasms of the central nervous system and clinical behavior. Simultaneous quantitation of DNA content and proliferation-associated nuclear antigen (p105) by flow cytometry was performed on paraffin-embedded tissues representing three major groups of central nervous system neoplasms--1) 21 astrocytic tumors, 2) 13 pituitary tumors, and 3) 19 meningiomas--and the results were correlated with clinical behavior. All 4 well-differentiated gliomas were diploid, while 3 of 9 anaplastic astrocytomas and 1 of 8 glioblastomas had a demonstrable aneuploid peak. Three of 13 pituitary tumors had an identifiable aneuploid peak, while only 2 of 19 meningiomas had an aneuploid DNA content. Cell-cycle analysis of the malignant gliomas revealed a significantly higher proliferative index (PI, %S + G2M) compared with the well-differentiated astrocytomas (P less than 0.05). Within the subgroup of diploid anaplastic astrocytomas, however, extended patient survival appeared to be associated with a higher PI. For diploid pituitary adenomas, the PI was consistently lower in the 3 tumors that recurred than it was in the remaining 8 adenomas. Nuclear antigen quantitation of diploid tumors showed a wide range of p105 expression in G0G1 cells, suggesting that, within each tumor, the cells are heterogeneous with respect to proliferative activity. Aneuploid nuclei of glial tumors showed enhanced expression of p105 relative to diploid cells of the same specimen. In pituitary tumors, the median G2M/G0G1 fluorescence ratio for p105 was significantly higher (P less than 0.05) for the 3 diploid recurrent tumors than for those that did not recur. These data support the assumption that the aggressive clinical course of malignant glial neoplasms may be related to an abnormal DNA stemline and/or an alteration in cell proliferative activity. Cell cycle analysis and measurement of p105 by this technique may provide information useful from both a prognostic standpoint and in directing adjuvant therapy.  相似文献   
6.
7.
Rete testis fluid (RTF) and luminal fluid collected by micropuncture at selected epididymal sites were analyzed to characterize the spectrum of proteins and to quantify the net gain or loss of total/bulk protein and androgen-binding protein (ABP) between successive regions within the ductus epididymidis. Based on one-dimensional SDS gel electrophoresis, the spectra of proteins in RTF and fluids from the proximal, central, and distal caput through proximal corpus epididymidis differed from each other. Concentrations of sperm, bulk protein, and ABP increased from the rete testis through the central caput epididymidis. Electron microscopic studies following intraluminal microinjections of RTF proteins conjugated to colloidal gold at specific sites in the excurrent ducts revealed that 145 times more protein-gold was endocytosed in the ductuli efferentes than in any of the four regions of the caput epididymidis. Thus, ductuli efferentes were the major extra-testicular site of endocytosis of bulk protein present in RTF; at least a portion of the uptake was specific. On a per sperm basis, the amount of protein present in the central caput epididymidis was less than 15% of that leaving the testis. Although most of the protein present in RTF (greater than or equal to 86 mg/d) must be absorbed in the ductuli efferentes and the initial segment of the epididymis and replaced by newly secreted proteins (greater than or equal to 34 mg/d), there was negligible loss of ABP in these regions. Net loss of ABP occurred primarily in the distal caput and proximal corpus epididymidis. These studies demonstrate that ABP is spared from endocytosis along with the bulk protein in RTF and conserved for functions in epididymal regions far distal to the site of bulk protein loss.  相似文献   
8.
9.
10.
Mediators of pulmonary injury induced by inhalation of bacterial endotoxin   总被引:4,自引:0,他引:4  
The purpose of this study has been to further define the pathophysiologic aspects of lung injury caused by the inhalation of endotoxin (LPS) using the morphometric approach to identify mediators that influence distal lung structure and function. Hamsters were divided into 3 groups 24 h prior to low dose LPS inhalation exposure (4 micrograms/m3 for 5 h): (1) pretreated with cobra venom factor to deplete complement in vivo, (2) pretreated with indomethacin to block prostaglandin production, and (3) untreated control group. Both pretreatments abolished LPS-induced decreases in lung volume as well as increases in capillary PMN and platelets seen in untreated control animals. Neither pretreatment had any effect on the LPS-induced decreases of other capillary leukocytes. Similarly, both methods of pretreatment failed to block increases in cellular interstitium of distal capillary septa induced with LPS alone. LPS provoked changes in capillary endothelium, especially seen as an increase in numerical density of endothelial pinocytotic vesicles. Decomplementation failed to alter this increase, but indomethacin pretreatment blocked the effect. Neither treatment had any effect on their size. Low dose LPS inhalation also altered pulmonary capillary permeability to a 125I-BSA probe, which was found in significantly greater amounts in LPS-exposed lungs than in those of saline aerosol control lungs, but was not present in the air space as evidenced by negligible counts in bronchoalveolar lavages. It is evident that endotoxin on the epithelial side of the air-blood barrier leads to changes on the other side of that barrier.(ABSTRACT TRUNCATED AT 250 WORDS)  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