全文获取类型
收费全文 | 26276篇 |
免费 | 1368篇 |
国内免费 | 65篇 |
专业分类
耳鼻咽喉 | 372篇 |
儿科学 | 2052篇 |
妇产科学 | 617篇 |
基础医学 | 2979篇 |
口腔科学 | 456篇 |
临床医学 | 1451篇 |
内科学 | 4852篇 |
皮肤病学 | 996篇 |
神经病学 | 1167篇 |
特种医学 | 1097篇 |
外科学 | 3898篇 |
综合类 | 919篇 |
一般理论 | 10篇 |
预防医学 | 1289篇 |
眼科学 | 1322篇 |
药学 | 2149篇 |
中国医学 | 141篇 |
肿瘤学 | 1942篇 |
出版年
2023年 | 153篇 |
2022年 | 392篇 |
2021年 | 745篇 |
2020年 | 413篇 |
2019年 | 479篇 |
2018年 | 693篇 |
2017年 | 458篇 |
2016年 | 664篇 |
2015年 | 603篇 |
2014年 | 939篇 |
2013年 | 1101篇 |
2012年 | 1566篇 |
2011年 | 1664篇 |
2010年 | 903篇 |
2009年 | 725篇 |
2008年 | 1245篇 |
2007年 | 1324篇 |
2006年 | 1145篇 |
2005年 | 1076篇 |
2004年 | 974篇 |
2003年 | 902篇 |
2002年 | 815篇 |
2001年 | 736篇 |
2000年 | 700篇 |
1999年 | 609篇 |
1998年 | 252篇 |
1997年 | 183篇 |
1996年 | 154篇 |
1995年 | 140篇 |
1994年 | 120篇 |
1993年 | 134篇 |
1992年 | 364篇 |
1991年 | 400篇 |
1990年 | 356篇 |
1989年 | 362篇 |
1988年 | 318篇 |
1987年 | 285篇 |
1986年 | 276篇 |
1985年 | 280篇 |
1984年 | 224篇 |
1983年 | 185篇 |
1979年 | 244篇 |
1978年 | 158篇 |
1977年 | 148篇 |
1976年 | 135篇 |
1975年 | 164篇 |
1974年 | 154篇 |
1973年 | 176篇 |
1972年 | 138篇 |
1971年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Administration of Embelin, an experimental antifertility agent, to male rats (20 mg/kg body wt/day, daily for 15 and 30 days), caused an elevation in the uptake of D-glucose, L-alanine, L-leucine, and calcium in the small intestinal segments. An increase was also noted in the intestinal brush border membrane (BBM)-associated enzymes, sucrase, lactase, maltase, alkaline phosphatase, and leucine aminopeptidase in both the intestinal homogenates and partially purified BBM preparations, particularly after 30-day administration of the drug. Embelin treatment also caused a significant increase in the microsomal glucose-6-phosphatase and the cytosolic enzyme, lactate dehydrogenase. In the Embelin-treated animals BBM-associated total lipids, phospholipids, cholesterol, triacylglycerol, unesterified fatty acids, ganglioside-sialic acids as well as the cholesterol/phospholipids molar ratio showed a considerable increase. All these changes in the Embelin-treated animals were restored back to the normal or near normal biochemical makeup when the drug therapy was withdrawn and the animals were allowed to recover for another 15 and 30 days, respectively. 相似文献
62.
S. C. Srivastava S. C. Gupta A. P. Singh 《Indian journal of otolaryngology and head and neck surgery》1993,45(4):188-190
In the present study 35 patients with preforated and 15 cases with intact ear drums, were studied and eustachian tube function
was assessed by Saccharine test. Bortnick-Miller test, and manual impedance audiometry. The merits and demerits of one over
the other were evaluated. It was observed thal more than one test when employed provides better information as every test
has its own advantages and limitations 相似文献
63.
Induction of MHC class II expression in recipient tissues caused by allograft rejection 总被引:2,自引:0,他引:2
MHC class II antigens (DR) are not commonly expressed on parenchymal cells of kidney and liver except when they are allografts undergoing rejection. The objective of this study was to determine whether allograft rejection can also induce DR upregulation in parenchymal cells of autologous recipient organs. Dogs had unilateral renal autografts to facilitate kidney sampling. All kidneys were tubular cell DR-negative. After 8-14 days each dog received a tubular cell DR-negative allograft. Tubular cell DR became positive in both allograft and autograft simultaneously, its onset and intensity correlating with blast cell infiltration and rejection in the allograft. Blast cells were first detected in the autograft after allograft nephrectomy, and then disappeared as autograft tubular cell DR diminished over the next 6-8 days. This was reproduced on repeat allografting. In 2 untreated dogs hepatocytes became positive on day 4, with no hepatic blast infiltrate. Four other dogs received cyclosporine immunosuppression. Allograft and autograft tubular cell DR, and hepatocyte DR, increased in all dogs, but were delayed while on CsA until onset of rejection despite transient earlier allograft blast infiltration. Downregulation in autograft and liver occurred together after allograft nephrectomy. An interferon-like substance appeared in plasma after allografting in association with the DR changes in native kidney and liver. Renal allorejection therefore induces upregulation of parenchymal DR expression in autologous liver and kidney of the recipient. It is probably mediated by an interferon-like substance derived from cells infiltrating the allograft. The effect is modified by CsA. 相似文献
64.
M K Chowdhury V M Gupta R Bairagi B N Bhattacharya 《European journal of clinical nutrition》1990,44(7):515-525
It is posited that diarrhoeal illness during one period has influence on diarrhoeal illness in a subsequent period. This relationship may potentially mask the association between malnutrition and subsequent diarrhoea. To test this, we analysed data on cross-sectional anthropometry in combination with data on diarrhoeal morbidity collected longitudinally in a community-based study of 1262 children (aged 6-60 months) during March-December, 1976, in Matlab, Bangladesh. The results confirmed the posited relationship between diarrhoeal morbidities in two consecutive periods and showed that the risks of diarrhoeal attack and longer diarrhoeal illness increased more than threefold during the 2 months following diarrhoeal illness during the preceding 2 months (previous diarrhoea). Children with no previous diarrhoea indicated a positive association between malnutrition and subsequent diarrhoea, but the pattern found among children with previous diarrhoea was not understandable. Logistic regression analyses performed separately for younger and older children showed that controlling for effects of previous diarrhoea, maternal illiteracy and household poverty, severe malnutrition as assessed by weight-for-age was found to be strongly associated with the risk of longer diarrhoeal illness in a 2-month interval in the age group 24-60 months; in the same age group the association with the risk of diarrhoeal attack was significant at the 10 per cent level. No such association for malnutrition, however, was found in the age group 6-23 months. 相似文献
65.
Bengal gram seed coat appeared to be a potent hypocholesterolemic/hypolipidemic agent in rabbits. When fed to hypercholesterolemic rabbits, it lowered hepatic cholesterol/lipid much more than in the control group. Aortic lipid levels were rather marginally increased but the increase was less in Bengal gram seed coat fed rabbits. Though seed coat of Bengal gram failed to prevent the development of atherosclerosis in hypercholesterolemic rabbits, but certainly it slowed down the process of its development. The hypocholesterolemic action of Bengal gram seed coat appeared to be due to the increased catabolism and excretion of cholesterol. 相似文献
66.
Wasif Ali Deepak K. Agarwal Sadiq S. Sikora Bhagwant R. Mittal Narendra Krishnani Md. Ibrarullah Ramesh K. Gupta Satyendra P. Kaushik 《Surgery today》1997,27(3):247-250
Duodenogastric reflux (DGR) has been implicated in several disease processes. The present study was carried out to document the incidence and evaluate the clinical significance of DGR after choledochoduodenostomy (CDD). A total of 13 patients who had undergone cholecystectomy with a standard side-to-side CDD for choledocholithiasis or chronic pancreatitis were studied by symptom evaluation, scintigraphy, endoscopy, and gastric mucosal histology at least 6 months after surgery. The scintigraphic findings were then compared with those of 10 patients who had undergone cholecystectomy alone. Only two patients (15%) had mild dyspeptic symptoms. The incidence of DGR after CDD was 69% compared to 20% in the cholecystectomy alone group (P < 0.05). In the majority of patients the DGR was only mild to moderate and the severity correlated well with the degree of endoscopic gastritis, but not with the clinical symptoms or histological findings. These results indicate that while CDD is associated with a high incidence of DGR, its occurrence does not produce significant clinical symptoms. 相似文献
67.
Human immunodeficiency virus type 1 (HIV-1) isolates from asymptomatic homosexual men and AIDS patients were compared for their in vitro biologic and genetic properties. Most of the HIV-1 isolates from asymptomatic men, but not from AIDS patients, failed to infect CD4+ H9 cells and phytohemagglutinin-stimulated peripheral blood lymphocytes. In a longitudinal study, serial HIV-1 isolates obtained from men who seroconverted to HIV-1 and later developed AIDS were able to infect H9 cells. In contrast, longitudinal isolates from men who remained asymptomatic did not infect H9 cells. HIV-1 isolates from AIDS patients in general exhibited increased production of intracellular viral DNA, RNA, and protein as compared to isolates from asymptomatic men. Cells infected with HIV-1 isolates from asymptomatic men produced very little gp120, p24, and p55 proteins as compared to those from AIDS patients. The overall restriction patterns of HindIII, Sac-1, Pst-1, EcoR1, and BamH1 were very similar between HIV-1 isolates from asymptomatic men and those from AIDS patients. However, the restriction endonuclease pattern of BglII was quite distinct for isolates from asymptomatic men as compared to AIDS patients. Preliminary studies mapped a unique BglII site in the gag region of most of the isolates from asymptomatic men, approximately 2.0 kb from the 5' end. Thus, HIV-1 isolates from asymptomatic subjects and from AIDS patients have distinct biologic and genetic properties which may be related to the various clinical outcomes of HIV-1 infection. 相似文献
68.
69.
70.
The genomic activity of nucleolar organizer regions (NORs) in eight human B-cell lymphoblastoid cell lines was studied following the routinely used Ag-NOR technique. The results demonstrate that (a) Ag-NORs are located in the short arms of D- and G-group chromosomes, (b) two out of eight cell lines have 66.7% and 49.0% of metaphases, respectively, with 9 to 10 active Ag-NORs, and (c) as a whole, Ag-NOR activity is much higher in B-cell lines as compared with conventional 72-hr peripheral blood lymphocyte (T-cell) harvests. 相似文献