全文获取类型
收费全文 | 5400篇 |
免费 | 298篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 220篇 |
妇产科学 | 140篇 |
基础医学 | 809篇 |
口腔科学 | 112篇 |
临床医学 | 515篇 |
内科学 | 1164篇 |
皮肤病学 | 105篇 |
神经病学 | 473篇 |
特种医学 | 192篇 |
外科学 | 718篇 |
综合类 | 42篇 |
一般理论 | 4篇 |
预防医学 | 379篇 |
眼科学 | 129篇 |
药学 | 408篇 |
中国医学 | 11篇 |
肿瘤学 | 274篇 |
出版年
2023年 | 30篇 |
2022年 | 71篇 |
2021年 | 123篇 |
2020年 | 68篇 |
2019年 | 111篇 |
2018年 | 125篇 |
2017年 | 98篇 |
2016年 | 103篇 |
2015年 | 131篇 |
2014年 | 145篇 |
2013年 | 217篇 |
2012年 | 358篇 |
2011年 | 372篇 |
2010年 | 204篇 |
2009年 | 163篇 |
2008年 | 322篇 |
2007年 | 359篇 |
2006年 | 337篇 |
2005年 | 275篇 |
2004年 | 277篇 |
2003年 | 262篇 |
2002年 | 231篇 |
2001年 | 84篇 |
2000年 | 81篇 |
1999年 | 86篇 |
1998年 | 43篇 |
1997年 | 36篇 |
1996年 | 39篇 |
1995年 | 34篇 |
1994年 | 29篇 |
1993年 | 26篇 |
1992年 | 56篇 |
1991年 | 55篇 |
1990年 | 48篇 |
1989年 | 51篇 |
1988年 | 47篇 |
1987年 | 41篇 |
1986年 | 41篇 |
1985年 | 48篇 |
1984年 | 47篇 |
1983年 | 36篇 |
1980年 | 27篇 |
1979年 | 29篇 |
1977年 | 27篇 |
1976年 | 30篇 |
1974年 | 30篇 |
1973年 | 32篇 |
1972年 | 28篇 |
1971年 | 21篇 |
1970年 | 22篇 |
排序方式: 共有5728条查询结果,搜索用时 15 毫秒
11.
I. Karel M. Filipec F. Vrabec J. Obenberger 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1986,224(5):481-485
Specular microscopic and histopathologic findings in the corneal endothelium were compared after the injection of liquid silicone into the anterior chamber of both eyes in 15 rabbits. The findings demonstrated serious damage to the endothelium in the area of contact of liquid silicone with the posterior surface of the cornea and disclosed some problems in the interpretation of specular microscopic findings. An abnormal endothelial mosaic can be probably found even in a zone of preserved intercellular borders or in a zone with a relief of the bases of extinct endothelial cells. 相似文献
12.
13.
Hans-Georg Elias Daniel C. Chung Nobuo Donkai Goetz P. Hellmann Karel Solc Katsutoshi Nagai 《Macromolecular chemistry and physics.》1987,188(3):537-560
1-O-3-(4-Vinylphenyl)propyl-β-D -glucopyranose ( 1 ) undergoes in water a closed association under formation of N-mers. The unimer/N-mer association is directly visible in the Schlieren pattern of ultracentrifugal synthetic boundary experiments. Association numbers and mass-concentration-based equilibrium constants of association were calculated from the variation of N-mer concentrations with unimer concentrations and from the concentration dependence of inverse apparent average molar masses as measured by both vapor phase osmometry and sedimentation equilibrium. Association numbers were also calculated from the combination of sedimentation coefficients with diffusion coefficients, sedimentation coefficients with intrinsic viscosities, and diffusion coefficients with interinsic viscosities as well as from the dependence of apparent mass-average molar masses on inverse apparent number-average molar masses. All methods gave in general different association numbers and equilibrium constants. The effect, which was not found for other non-ionic amphiphiles, is probably due to the existence of consecutive equilibria between the unimer and a low molar mass P-mer which associates to a higher molar mass R-mer. Viscosity data are in agreement with the picture of a spherical micelle for the dominant P-mers with about 10 water molecules per glucose residue. The micellization of 1 is both enthalpy- and entropy-driven, in contrast to the micellization of 1-O-octyl-β-D -glucopyranose which is a strictly entropy-driven process. 相似文献
14.
Pallavi Parashar Anthony Musella Timothy Novak Robert O Greer 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(4):e66-e70
Melorheostosis is a rare sclerosing bone dysplasia that is characterized by a localized, diffuse thickening of the cortical bone. This condition usually affects the appendicular skeleton and associated soft tissue and rarely affects the craniofacial complex. The etiology of this condition is obscure. Diagnosis of melorheostosis relies on clinical, radiographic, and histological correlation. Only 8 cases of melorheostosis involving the craniofacial complex have been reported. We report 2 new cases of isolated melorheostosis involving the maxilla and mandible, together with differential diagnostic considerations. To our knowledge, involvement of the maxilla only has not been previously reported. 相似文献
15.
Alain Deschamps Steven B Backman Vera Novak Gilles Plourde Pierre Fiset Daniel Chartrand 《The Journal of pharmacology and experimental therapeutics》2002,300(1):112-117
Edrophonium, an anticholinesterase, exerts a biphasic effect on cardiovascular autonomic drive in humans (lower doses enhance; higher doses reduce). Twenty-five anesthetized, mechanically respired (10 breaths. min(-1), constant tidal volume) patients were given either saline (n = 10) or edrophonium (0.01-1.0 mg. kg(-1), n = 15) following surgery. ECG, radial arterial pressure, and respiratory rate were sampled at 250 Hz to obtain time series for consecutive R-R intervals (RRIs), and systolic (SBP) and diastolic blood pressure (DBP). A Wigner distribution was used for time frequency mapping of spectral powers at high (HFP, 0.15-0.5 Hz) and low (LFP, 0.0-0.05 Hz) frequency. Edrophonium produced a dose-dependent decrease in heart rate [baseline 66.8 +/- 1.9 (S.E.M.) beats per minute; maximum decrease to 55.8 +/- 1.4 beats per minute with 1.0 mg. kg(-1), P < 0.01]. HFP of the RRI increased at low doses (0.2-0.4 mg. kg(-1); maximum increase to 111.0 +/- 58.2% baseline; P < 0.01) but decreased (-49.5 +/- 35.5% baseline; P < 0.01) at higher (1.0 mg. kg(-1)) doses. Edrophonium had no effect on SBP and DBP. HFP of SBP decreased with increasing doses (maximal decrease to -26.2 +/- 7.5% baseline, P < 0.01, 1.0 mg. kg(-1)). LFP of SBP was also decreased (-46.3 +/- 10.9% baseline, P < 0.01, 1.0 mg. kg(-1)). Edrophonium may enhance (lower dose) or reduce (higher dose) cardiovascular autonomic drive in humans, as evidenced by the significant changes it evokes in HFP of the RRI (parasympathetic drive), and in the HFP and LFP of SBP (sympathetic drive). These observations may account for the modest autonomic side effects of edrophonium when this drug is used clinically. 相似文献
16.
Gerlof D. Valk Arnoud C. Kappelle Aimée M. L. Tjon-A-Tsien Bert Bravenboer Karel Bakker Robert P. J. Michels Cees M. Groenhout Frederik W. Bertelsmann 《Journal of neurology》1996,243(3):257-263
The efficacy of the neurotrophic peptide ORG 2766 in diabetic patients with polyneuropathy was evaluated in a double-blind, placebo-controlled, multicentre trial. One hundred and twenty four patients were randomised in five groups to receive 0.1, 0.4, 2 or 5 mg ORG 2766 or placebo, once daily, administered subcutaneously 52 weeks. Thermal discrimination thresholds (TDT) and vibration perception thresholds (VPT), motor and sensory nerve conduction velocity, Hoffmann reflex, heart rate variation during deep breathing and heart rate response after standing up, neurological examination score and neuropathic symptom score were determined at baseline and after 17, 34 and 52 weeks of treatment. Of the nerve function indices studied, at week 52 the TDTwarmth of the hand in the ORG 2766 0.1, 0.4 and 5 mg groups and the TDTcold of the foot in the ORG 2766 0.1 and 0.4 mg groups significantly improved compared with placebo. Further significant improvement as compared with placebo was observed in the paraesthesia score at week 34 and week 52 in the ORG 2766 2 mg group. Only at week 34 had both the heartbeat variation during deep breathing and the VPT of the foot in the ORG 2766 0.1 mg group improved significantly, compared with placebo. No further statistically significant differences were observed at time for the other measures. No adverse reactions were observed. The only recorded drug-induced side effect was pain at the injection site. Taking all measures of efficacy into account, the statistically significant results observed did not show consistency within each measure. Therefore, it is concluded that ORG 2766, in contrast to earlier reports, is not effective in treating diabetic polyneuropathy. 相似文献
17.
Mechanistic studies were conducted to examine the relationship between oxidative membrane protein damage, altered Ca2+ homeostasis, and changes in the levels of plasma membrane-bound Ca(2+)-activated neutral protease, microCANP. Alterations in the levels of plasma membrane-bound microCANP in erythrocytes and hemolysate following cumene hydroperoxide (CHP) insult were monitored using SDS-PAGE and immunoblot analyses. Free radical scavengers, antioxidant and EGTA effects on membrane-bound microCANP levels in CHP-treated cells and hemolysate were also examined. CHP (2 mM) addition to red cells caused a significant decrease/loss in intensity of numerous protein bands in the SDS-PAGE pattern, to include bands 1, 2, 2.1, 4.1, 4.2, and an approximately 60-kDa protein. N-acetylcysteine (20 mM), dithiothreitol (50 mM), and dimethylthiourea (50 mM) diminished CHP-mediated membrane protein damage; in contrast, dimethylfuran (50 mM) exacerbated CHP-mediated membrane protein damage. Dimethylsulfoxide (50 mM) was without significant effect. The free radical scavengers and antioxidants differentially affected membrane-bound microCANP levels largely in parallel with their ability to modulate membrane protein damage. Immunoblot analysis of 1 mM CHP-treated red cells revealed a time-dependent loss of membrane-bound microCANP, with a complete loss of microCANP monitored at 8 hr. Treatment of erythrocytes with CHP also resulted in concentration-dependent alterations in the level of membrane-bound microCANP: at 0.5 or 1.0 mM CHP a decreased level of membrane-bound microCANP was detected relative to control, whereas an increase in the level of bound enzyme was monitored from 2 to 4 mM CHP. CHP addition to hemolysate produced a decrease in membrane-bound microCANP levels comparable to that observed with erythrocytes; addition of the Ca2+ chelator EGTA or Calpain Inhibitor I (N-acetyl-leucyl-leucyl-leucyl-nor-leucinal) to hemolysate effectively inhibited this decrease. In contrast, treatment of erythrocytes with Ca2+ in the presence of the Ca2+ ionophore A23187 resulted in change in the SDS-PAGE protein bands and membrane-bound microCANP levels that were comparable to those produced by CHP. Inclusion of EGTA in this system prevented microCANP binding. These data provide evidence for membrane damage and concomitant dynamic alterations in membrane-bound microCANP levels in the red cell or hemolysate following oxidative insult, and show that this process can be modulated by free radical scavengers and antioxidant, simulated by treating cells with Ca2+ in the presence of ionophore, and inhibited by EGTA or Calpain Inhibitor I. 相似文献
18.
Ixodes dammini Spielman, Clifford, Piesman & Corwin collected from a study site in southwestern Wisconsin were examined for Borrelia burgdorferi infection. Adult spirochete infection rates varied seasonally (38.1%, spring 1990; 60.3%, fall 1990; 41.2%, spring 1991) and were similar to or higher than rates reported in various studies from the northeastern United States. Statistical comparison of seasonal infection rates indicated a significant difference between the fall 1990 adult population and the subsequent overwintered population of the same cohort (spring 1991). Additionally, a significant decrease in the intensity of spirochete infection was observed in the overwintered adult sample. 相似文献
19.
Lucie Sobolová Nina Skottová Rostislav Vecera Karel Urbánek 《Pharmacological research》2006,53(2):104-112
This study evaluated the influence of silymarin (SM) and polyphenolic fraction (PF) of silymarin on cholesterol absorption in rats fed on high cholesterol diet (HCD). HCD induced a remarkable increase in hepatic, plasma, VLDL and LDL cholesterol, a decrease in HDL cholesterol and an elevation in triacylglycerol (TAG) levels in plasma, VLDL and in the liver. SM and PF were administered as dietary supplements (1.0%) in HCD for 18 days. Intestinal cholesterol absorption was measured by dual-isotope plasma ratio method, which calculates percent of cholesterol absorption from the ratio of two labelled cholesterol doses, one given intragastrically (14C) and one intravenously (3H). Silymarin and PF significantly reduced cholesterol absorption in rats fed on HCD and caused significant decreases in plasma and VLDL cholesterol and content of cholesterol and TAG in the liver. The level of HDL cholesterol was significantly increased after silymarin, but not after administration of PF. The levels of TAG in plasma and VLDL were not affected by either silymarin or PF. These results suggest that the inhibition of cholesterol absorption caused by silymarin and its polyphenolic fraction could be a mechanism contributing to the positive changes in plasma cholesterol lipoprotein profile and in lipid content in liver. 相似文献
20.
Professional involvement in sexuality counseling for patients with spinal cord injuries 总被引:1,自引:0,他引:1
A national survey was conducted to determine how occupational therapists and rehabilitation nurses conduct sexuality counseling in practice settings with spinal cord-injured patients. A review of the literature and results from the survey demonstrated a high priority concern for sexuality counseling in the total rehabilitation of the spinal cord-injured patient; however, many of the professionals surveyed did not conduct sexuality counseling as part of their job. This study provides data comparing the sexuality counseling approach taken by these two disciplines and identifies ways to eliminate the incongruities between recommendations made in the literature and actual clinical practice. 相似文献