全文获取类型
收费全文 | 9326篇 |
免费 | 427篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 249篇 |
妇产科学 | 145篇 |
基础医学 | 1073篇 |
口腔科学 | 173篇 |
临床医学 | 614篇 |
内科学 | 2444篇 |
皮肤病学 | 157篇 |
神经病学 | 1038篇 |
特种医学 | 304篇 |
外科学 | 1824篇 |
综合类 | 26篇 |
预防医学 | 211篇 |
眼科学 | 200篇 |
药学 | 441篇 |
中国医学 | 15篇 |
肿瘤学 | 837篇 |
出版年
2023年 | 45篇 |
2022年 | 81篇 |
2021年 | 197篇 |
2020年 | 116篇 |
2019年 | 173篇 |
2018年 | 222篇 |
2017年 | 142篇 |
2016年 | 172篇 |
2015年 | 162篇 |
2014年 | 242篇 |
2013年 | 287篇 |
2012年 | 453篇 |
2011年 | 461篇 |
2010年 | 285篇 |
2009年 | 255篇 |
2008年 | 409篇 |
2007年 | 471篇 |
2006年 | 453篇 |
2005年 | 466篇 |
2004年 | 436篇 |
2003年 | 432篇 |
2002年 | 409篇 |
2001年 | 245篇 |
2000年 | 266篇 |
1999年 | 215篇 |
1998年 | 114篇 |
1997年 | 95篇 |
1996年 | 77篇 |
1995年 | 75篇 |
1994年 | 84篇 |
1993年 | 59篇 |
1992年 | 186篇 |
1991年 | 183篇 |
1990年 | 159篇 |
1989年 | 173篇 |
1988年 | 156篇 |
1987年 | 123篇 |
1986年 | 119篇 |
1985年 | 132篇 |
1984年 | 105篇 |
1983年 | 83篇 |
1979年 | 75篇 |
1977年 | 45篇 |
1976年 | 48篇 |
1974年 | 50篇 |
1973年 | 55篇 |
1972年 | 51篇 |
1970年 | 53篇 |
1969年 | 51篇 |
1968年 | 44篇 |
排序方式: 共有9813条查询结果,搜索用时 109 毫秒
71.
72.
Tetsushi Furukawa Tei-ichi Yamane Tomoko Terai Yoshifumi Katayama Masayasu Hiraoka 《Pflügers Archiv : European journal of physiology》1996,431(4):504-512
The role of the cytoskeleton in the rundown and reactivation of adenosine triphosphate (ATP) sensitive K+ channels (KATP channels) was examined by perturbing selectively the intracellular surface of inside-out membrane patches excised from guinea-pig ventricular myocytes. Actin filament-depolymerizing agents (cytochalasins and desoxyribonuclease I) accelerated channel rundown, while actin filament stabilizer (phalloidin) or phosphatidylinositol biphosphate (PIP2; inhibitor of F-actin-severing proteins) inhibited spontaneous and/or Ca2+-induced rundown. When rundown was induced by cytochalasin D or by long exposure to high Ca2+, channel activity could not be restored by exposure to MgATP, but application of F-actin with MgATP could reinstitute channel activity. The processes of rundown and reactivation of cardiac KATP channels may thus be influenced by the assembly and disassembly of the actin cytoskeletal network, which provides a novel regulatory mechanism of this channel. 相似文献
73.
Central distribution of efferent and afferent components of the pudendal nerve in rat 总被引:6,自引:0,他引:6
Summary Central distribution of efferent and afferent components of the pudendal nerve was examined in the rat by the horseradish peroxidase (HRP) method after HRP application to the central cut end of the pudendal nerve. The pudendal motoneurons were located in the dorsolateral, dorsomedial and lateral groups at L5 and L6. Each of the dorsolateral and dorsomedial groups constituted a slender longitudinal cell column. Pudendal motoneurons in the lateral group were scattered at L5, rostrodorsally to the dorsolateral group. The neurons in the dorsolateral and lateral groups were labelled with HRP applied to the nerve branch innervating the ischiocavernosus and sphincter urethrae muscles. The neurons in the dorsomedial group were labelled with HRP applied to the branch supplying the sphincter ani externus and bulbospongiosus muscles. Some dendrites of pudendal motoneurons in the dorsomedial group extended to the contralateral dorsomedial group. These crossing dendrites were observed not only in male rats but also in female. The average number of the pudendal motoneurons in the dorsolateral and dorsomedial groups were larger in male rats than in female. A few neurons of the intermediolateral nucleus at upper L6 were also labelled with HRP applied to the dorsalis penis (clitoridis) nerve. Axon terminals of the pudendal nerve were distributed, bilaterally with an ipsilateral predominance, to the gracile nucleus, as well as to the dorsal horn and dorsal commissural gray from L4 to S2. A few labelled axons were seen in the intermediolateral nucleus at L6 and S1. Axon terminals from the dorsalis penis nerve were distributed more medially in the dorsal horn than those from the perinealis nerve. 相似文献
74.
75.
76.
Kazuo Tamura Yoshihiro Yamamoto Yoshifumi Saeki Jun-ichi Furuyama Joji Utsunomiya 《Human mutation》1993,2(6):478-484
Germline mutations in patients with familial adenomatous polyposis were analyzed by polymerase chain reaction (PCR) amplification of the adenomatous polyposis coli gene. PCR products from heterozygous patients for deletions of this gene formed four distinct bands on polyacrylamide gel electrophoresis. The four fragments were subsequently purified and both strands of each fragment were directly sequenced, using an automated DNA sequencer and the same primers as those for PCR amplification. It was found that the two slower migrating fragments were “bulge” heteroduplexes, while the other two were homoduplexes made up of two wild-type strands and two deletion-mutant strands, respectively. The sites of deletions in the adenomatous polyposis coli gene could be exactly determined in four of the five patients. In an attempt to identify deletion-carriers of familial adenomatous polyposis at the presymptomatic stage, a family study was also carried out, and two children were found to have the same mutations as those of their affected parents. The direct sequencing of heteroduplex fragments generated during PCR amplification is a potentially useful method for detecting mutations of not only the adenomatous polyposis coli gene but also many other genes of genetic diseases. © 1993 Wiley-Liss, Inc. 相似文献
77.
We investigated the effects of suppression of complement activation at C3 level and inhibition of C5a on acute synovitis in rats. Acute synovitis was induced in Wistar rats by intra-articular (i.a.) injection into one knee of 0.3 mg of MoAb 6D1 (anti-rat CD59 antibody). In the treatment groups, soluble CR1 (sCR1) or C5a receptor (C5aR) antagonist was administered intra-articularly or intravenously and effects on the course of the acute synovitis were monitored. Synovitis induced by 6D1 was characterized by joint swelling, thickening of synovial tissue, cellular infiltration and deposition of membrane attack complex (MAC) on the synovial surface. Neither inflammatory change nor MAC deposition was found in rats which received an i.a. injection of sCR1 to suppress complement activity in the joint. Intra-articular injection of sCR1 did not reduce plasma complement activity. Intravenous administration of sCR1 suppressed plasma complement activity but had no effect on the course of the arthritis and synovitis with MAC deposition was observed. Neither i.a. nor i.v. injection of C5aR antagonist had any suppressive effects on inflammatory change or MAC deposition in synovium. The data show that inflammatory change induced by 6D1 was mediated by local complement activation and was not accompanied by systemic complement activation. C5a generation was not responsible for the observed inflammation, suggesting that other complement activation products, possibly MAC, mediate the inflammatory change observed in this model of acute synovitis in rats. 相似文献
78.
Carbonic anhydrase in the red blood cell and in the pulmonary endothelium facilitates the elimination of CO2 in the lungs. Although a carbonic anhydrase inhibitor, such as acetazolamide which is frequently used in patients with glaucoma or with metabolic alkalosis, is known to impair the CO2 elimination in the lungs, the dose-response curve of CO2 elimination with acetazolamide has not been well documented in CO2 homeostasis. In the present study, the effects of inhibited carbonic anhydrase were tested in 8 anesthetized dogs; various dosages of acetazolamide were used. When the administered clinical dosage of acetazolamide increased from 5 to 20 mg/kg, PaCO2, PVCO2, arterial-alveolar PCO2 difference (a-ADCO2), and physiological VD/VT ratio increased progressively to 52.0 +/- 2.1 Torr, 58.0 +/- 3.0 Torr, 23.4 +/- 1.2 Torr, and by 19.2 +/- 1.8% (S.E.) respectively, whereas inhibition rate of red blood cell carbonic anhydrase (RCA) activity increased progressively to 73.1 +/- 2.1% (S.E.). On the other hand, PACO2 decreased to 27.1 +/- 1.8 Torr (S.E.) upon the first injection of 5 mg/kg of acetazolamide, but PACO2 did not change further upon 3 additional 5 mg/kg injections. Mixed venous-arterial PCO2 difference [V-a)PCO2), VCO2, and anatomical VD/VT ratio were unchanged by the administration of any doses of acetazolamide. 相似文献
79.
Tetsuo Takaishi Takashi Ono Yoshifumi Yasuda 《European journal of applied physiology》1992,65(4):335-339
Summary The surface electromyogram (EMG) from active muscle and oxygen uptake (
) were studied simultaneously to examine changes of motor unit (MU) activity during exercise tests with different ramp increments. Six male subjects performed four exhausting cycle exercises with different ramp slopes of 10, 20, 30 and 40 W · min–1 on different days. The EMG signals taken from the vastus lateralis muscle were stored on a digital data recorder and converted to obtain the integrated EMG (iEMG). The
was measured, with 20-s intervals, by the mixing chamber method. A non-linear increase in iEMG against work load was observed for each exercise in all subjects. The break point of the linear relationship of iEMG was determined by the crossing point of the two regression lines (iEMGbp). Significant differences were obtained in the exercise intensities corresponding to maximal oxygen uptake (
) and the iEMGbp between 10 and 30, and 10 and 40 W · min –1 ramp exercises (P < 0.05). However, no significant differences were obtained in
and
corresponding to the iEMGbp during the four ramp exercises. With respect to the relationship between
and exercise intensity during the ramp increments, the
-exercise intensity slope showed significant differences only for the upper half (i.e. above iEMGbp). These results demonstrated that the
and
at which a nonlinear increase in iEMG was observed were not varied by the change of ramp slopes but by the exercise intensity corresponding to
and the iEMGbp was varied by the change of ramp slopes. In addition, the significant differences in the
exercise intensity slopes for the upper half of the tests would suggest that the recruitment patterns of MU and/or muscle metabolic state might be considerably altered depending upon the ramp slope increments. 相似文献
80.
Cross education of muscular strength during unilateral resistance training and detraining 总被引:2,自引:0,他引:2
Shima N Ishida K Katayama K Morotome Y Sato Y Miyamura M 《European journal of applied physiology》2002,86(4):287-294
Abstract. The purpose of the present study was to examine the changes in maximum voluntary isometric contraction (MVC) in the contralateral
untrained limb during unilateral resistance training and detraining, and to examine the factors inducing these changes by
means of electrophysiological techniques. Nine healthy males trained their plantar flexor muscles unilaterally 4 days·week–1 for 6 weeks using 3 sets of 10–12 repetitions at 70–75% of one-repetition maximum a day, and detrained for 6 weeks. Progressive
unilateral resistance training significantly (P<0.05) increased MVC, integrated electromyogram (iEMG), and voluntary activation in the trained and contralateral untrained
limbs. The changes in MVC after training were significantly correlated with the changes in iEMG in both limbs. No significant
changes occurred in MVC, voluntary activation, and iEMG in the contralateral limb after detraining. The changes in MVC after
detraining did not correlate with the changes in voluntary activation or iEMG in either limb. Training and detraining did
not alter twitch and tetanic peak torques in either limb. These results suggest that the mechanisms underlying cross education
of muscular strength may be explained by central neural factors during training, but not solely so during detraining.
Electronic Publication 相似文献