全文获取类型
收费全文 | 112455篇 |
免费 | 42527篇 |
国内免费 | 394篇 |
专业分类
耳鼻咽喉 | 2069篇 |
儿科学 | 4707篇 |
妇产科学 | 1227篇 |
基础医学 | 21123篇 |
口腔科学 | 5710篇 |
临床医学 | 15273篇 |
内科学 | 29466篇 |
皮肤病学 | 8465篇 |
神经病学 | 15570篇 |
特种医学 | 4490篇 |
外科学 | 18603篇 |
综合类 | 333篇 |
一般理论 | 33篇 |
预防医学 | 5533篇 |
眼科学 | 2255篇 |
药学 | 9133篇 |
1篇 | |
中国医学 | 1390篇 |
肿瘤学 | 9995篇 |
出版年
2023年 | 274篇 |
2022年 | 773篇 |
2021年 | 2360篇 |
2020年 | 5528篇 |
2019年 | 11426篇 |
2018年 | 10873篇 |
2017年 | 11984篇 |
2016年 | 12945篇 |
2015年 | 13298篇 |
2014年 | 13547篇 |
2013年 | 14231篇 |
2012年 | 7373篇 |
2011年 | 7078篇 |
2010年 | 10684篇 |
2009年 | 6825篇 |
2008年 | 4312篇 |
2007年 | 3007篇 |
2006年 | 2828篇 |
2005年 | 2521篇 |
2004年 | 2227篇 |
2003年 | 2011篇 |
2002年 | 1934篇 |
2001年 | 1564篇 |
2000年 | 1478篇 |
1999年 | 889篇 |
1998年 | 283篇 |
1997年 | 249篇 |
1996年 | 228篇 |
1995年 | 180篇 |
1994年 | 159篇 |
1993年 | 131篇 |
1992年 | 273篇 |
1991年 | 211篇 |
1990年 | 186篇 |
1989年 | 197篇 |
1988年 | 154篇 |
1987年 | 121篇 |
1986年 | 108篇 |
1985年 | 88篇 |
1984年 | 87篇 |
1983年 | 58篇 |
1982年 | 54篇 |
1981年 | 55篇 |
1980年 | 44篇 |
1979年 | 61篇 |
1978年 | 50篇 |
1977年 | 50篇 |
1974年 | 38篇 |
1972年 | 45篇 |
1971年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Henry Ho‐Lung Chan 《Clinical & experimental optometry》2005,88(6):410-414
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma. 相似文献
22.
E. Wieczerzak E. Jankowska S. Rodziewicz‐Motowido A. Giedo J. giewka Z. Grzonka M. Abrahamson A. Grubb D. Brmme 《Chemical biology & drug design》2005,66(Z1):1-11
Abstract: We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor–enzyme complex, Ki, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z‐Arg‐Leu‐His‐Agly‐Ile‐Val‐OMe ( 7 ) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7 . We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K. 相似文献
23.
24.
25.
26.
Teng-Yi Huang Hsiao-Wen Chung Fu-Nien Wang Cheng-Wen Ko Cheng-Yu Chen 《Magnetic resonance in medicine》2004,51(2):243-247
In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished. 相似文献
27.
Abstract – Traumatic dental injuries often occur to the teeth and their supporting tissues and they are the main reasons for emergency visit to a dental clinic. Management of a fracture depends on its position and the extent of root involvement. Horizontal root fractures are not seen frequently and the treatment consists of reduction and long‐term rigid fixation of the coronal segment. The present case demonstrates the successful management of two horizontally fractured maxillary central incisors with a follow‐up period of 9 months. 相似文献
28.
Aims To measure the prevalence of low high‐density lipoprotein (HDL)‐cholesterol (men < 1.03 mmol/l; women < 1.29 mmol/l) in European Type 2 diabetic patients receiving treatment for dyslipidaemia. Methods The pan‐European Survey of HDL‐cholesterol measured lipids and other cardiovascular risk factors in 3866 patients with Type 2 diabetes and 4436 non‐diabetic patients undergoing treatment for dyslipidaemia in 11 European countries. Results Diabetic patients were more likely to be obese or hypertensive than non‐diabetic patients. Most patients received lifestyle interventions (87%) and/or a statin (89%); treatment patterns were similar between groups. Diabetic patients had [means (SD)] lower HDL‐cholesterol [1.22 (0.37) vs. 1.35 mmol/l (0.44) vs. non‐diabetic patients, P < 0.001] and higher triglycerides [2.32 (2.10) vs. 1.85 mmol/l (1.60), P < 0.001]. More diabetic vs. non‐diabetic patients had low HDL‐cholesterol (45% vs. 30%), high triglycerides (≥ 1.7 mmol/l; 57% vs. 42%) or both (32% vs. 19%). HDL‐cholesterol < 0.9 mmol/l was observed in 18% of diabetic and 12% of non‐diabetic subjects. Differences between diabetic and non‐diabetic groups were slightly greater for women. LDL‐ and total cholesterol were lower in the diabetic group [3.02 (1.05) vs. 3.30 mmol/l (1.14) and 5.12 (1.32) vs. 5.38 mmol/l (1.34), respectively, P < 0.001 for each]. Conclusions Low HDL‐cholesterol is common in diabetes: one in two diabetic women has low HDL‐cholesterol and one diabetic man in four has very low HDL‐cholesterol. Management strategies should include correction of low HDL‐cholesterol to optimize cardiovascular risk in diabetes. 相似文献
29.
New long-acting beta 2-adrenoceptor agonists, formoterol and salmeterol, may soon appear in several European countries for treatment of asthma. This review examines currently available information and compares the basic pharmacology and describes the clinical effects of these new drugs. The long duration of bronchodilation seen in clinical studies seems to be similar, whereas in isolated tissues there might be a difference in the binding characteristics to the beta 2-adrenoceptor. Long-acting beta 2-agonists could have an inhibitory effect on inflammatory events related to asthma, but the clinical relevance of these effects is not clear at present. Long-term studies up to one year with both new drugs have not shown any unexpected side-effects, and no tachyphylaxis to beta-adrenoceptor stimulation has been reported. Patients appear to strongly prefer the new drugs compared to the short-acting beta 2-agonists. The potential place for these drugs in the treatment of asthma is discussed and some pitfalls pointed out. It is likely that the long-acting beta 2-agonists will be beneficial to many asthmatic patients. 相似文献
30.
Chick and rat experiments were conducted to determine the efficacy of L-2-oxothiazolidine-4-carboxylate (OTC) as a cysteine (Cys) precursor for growth and hepatic glutathione (GSH) biosynthesis. Isosulfurous graded increments of OTC and Cys were added to Cys-free purified amino acid diets that were adequate in methionine. Curvilinear responses to both Cys and OTC for chicks and rats were obtained. Hepatic GSH accumulated in chicks only at dietary Cys levels above 0.10%. In rats, hepatic GSH increased linearly as dietary Cys content increased from deficient to adequate and from adequate to excessive. Utilization of OTC by chicks was as efficacious as isosulfurous levels of Cys for growth and hepatic GSH biosynthesis. In rats, OTC was slightly inferior to Cys for growth and hepatic GSH biosynthesis. Exponential regression slope-ratio growth efficacy values for OTC were 78.5% for chicks and 70.2% for rats; multiple linear regression slope-ratio GSH biosynthesis efficacy values were 80.3% for chicks and 83.7% for rats. It is concluded that orally administered OTC is active as a Cys precursor. 相似文献