全文获取类型
收费全文 | 161609篇 |
免费 | 10323篇 |
国内免费 | 1213篇 |
专业分类
耳鼻咽喉 | 2255篇 |
儿科学 | 3025篇 |
妇产科学 | 3744篇 |
基础医学 | 24079篇 |
口腔科学 | 3342篇 |
临床医学 | 15264篇 |
内科学 | 30797篇 |
皮肤病学 | 4345篇 |
神经病学 | 12069篇 |
特种医学 | 8088篇 |
外科学 | 21895篇 |
综合类 | 2159篇 |
现状与发展 | 5篇 |
一般理论 | 81篇 |
预防医学 | 9724篇 |
眼科学 | 4316篇 |
药学 | 13678篇 |
中国医学 | 1597篇 |
肿瘤学 | 12682篇 |
出版年
2023年 | 986篇 |
2022年 | 2740篇 |
2021年 | 4831篇 |
2020年 | 2465篇 |
2019年 | 3588篇 |
2018年 | 4410篇 |
2017年 | 3235篇 |
2016年 | 4187篇 |
2015年 | 5637篇 |
2014年 | 6916篇 |
2013年 | 8375篇 |
2012年 | 12654篇 |
2011年 | 12293篇 |
2010年 | 7253篇 |
2009年 | 6069篇 |
2008年 | 9262篇 |
2007年 | 9126篇 |
2006年 | 8380篇 |
2005年 | 7986篇 |
2004年 | 7132篇 |
2003年 | 6192篇 |
2002年 | 5380篇 |
2001年 | 4392篇 |
2000年 | 4041篇 |
1999年 | 3273篇 |
1998年 | 1312篇 |
1997年 | 989篇 |
1996年 | 953篇 |
1995年 | 864篇 |
1994年 | 756篇 |
1993年 | 644篇 |
1992年 | 1583篇 |
1991年 | 1575篇 |
1990年 | 1360篇 |
1989年 | 1242篇 |
1988年 | 1156篇 |
1987年 | 1032篇 |
1986年 | 1012篇 |
1985年 | 885篇 |
1984年 | 645篇 |
1983年 | 566篇 |
1982年 | 399篇 |
1981年 | 377篇 |
1980年 | 339篇 |
1979年 | 522篇 |
1978年 | 407篇 |
1977年 | 388篇 |
1976年 | 343篇 |
1974年 | 359篇 |
1973年 | 329篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Phosphorylation of neurofilament proteins and chromatolysis following transection of rat sciatic nerve 总被引:7,自引:0,他引:7
M E Goldstein H S Cooper J Bruce M J Carden V M Lee W W Schlaepfer 《The Journal of neuroscience》1987,7(5):1586-1594
States of phosphorylation of neurofilament proteins were examined in the perikarya of rat sensory and motor neurons between 3 and 28 d following either a distal transection [6-7 cm from the L4-L5 dorsal root ganglia (DRG)] or a proximal transection (1-2 cm from the L4-L5 DRG) of the sciatic nerve. Paraffin sections of the right (experimental) and left (control) L4 and L5 DRG from animals with unilateral transection of the right distal sciatic nerve were stained immunocytochemically with monoclonal antibodies to phosphorylation-dependent (NF-P), dephosphorylation-dependent (NF-dP), or phosphorylation-independent (NF-ind) epitopes on the largest (NF200), mid-sized (NF150), or smallest (NF68) neurofilament protein subunits. Increased immunoreactivity to NF-P on NF200 and NF150 was detected in experimental DRC at 10 d, peaking by 20 d, and declining to near control levels by 28 d. Conversely, immunoreactivity to NF-dP declined in experimental DRG beginning at 6 d, reaching a maximum decline at 10-16 d, and returning to near control levels by 28 d. Immunocytochemical changes were confirmed with biochemical studies on tissue homogenates that demonstrated an increase of immunoreactivity to NF-P and a decrease of reactivity to NF-dP in the experimental DRG. Changes in immunoreactivities to NF-P and NF-dP were observed only in the perikarya of large neurons and were closely associated with chromatolytic changes in these neurons. Marked enhancement of chromatolysis, as well as the immunoreactivities to NF-P and NF-dP, occurred following a proximal (left side) versus distal (right side) transection in the same animal.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
192.
Comparative testicular toxicity of bis(2-methoxyethyl) ether and 2-methoxyethanol in rats 总被引:2,自引:0,他引:2
Male rats were exposed to 0, 110, 370, or 1100 ppm bis(2-methoxyethyl)ether (diglyme) 6 h/day, 5 days/week for 2 weeks. One group of male rats was exposed to 300 ppm 2-methoxyethanol (2-ME) for 2 weeks as a positive control. Exposed rats were killed after 10 days of exposure and 14, 42, or 84 days post-exposure (PE), respectively. At 110 ppm diglyme, spermatocytes in pachytene and meiotic division at spermatogenic stages XII-XIV were mainly affected. At 370 ppm diglyme, affected germ cells were similar to those seen at 110 ppm diglyme, but round spermatids at spermatogenic stages I-VII were also affected. The testes regained normal spermatogenesis by 84 days PE. At 1100 ppm diglyme or 300 ppm 2-ME, marked testicular atrophy was found affecting all spermatogenic stages. Damaged seminiferous tubules were lined with regenerating pachytene spermatocytes at 14 days PE and with spermatocytes and round spermatids after 42 days PE. Most but not all testes in rats exposed to 300 ppm 2-ME or 1100 ppm diglyme had normal morphology after 84 days PE. Based on the observation of germ cell damage, spermatozoa population in the epidymal tubules, reversibility of spermatogenesis after various PE periods, testicular toxicity induced by 300 ppm 2-ME was more severe than that seen at 370 ppm diglyme but was slightly less remarkable than that of 1100 ppm diglyme. 相似文献
193.
Reported here is a case of axillary artery aneurysm secondary to crutch trauma as a source of emboli to the upper extremity. This patient along with several reported in the literature was initially diagnosed and treated for brachial artery embolism. It is believed that awareness of this entity as a cause of forearm and hand ischemia is important in planning the appropriate surgical therapy. 相似文献
194.
We have evaluated the in vitro effects of bromocriptine (Br), on the hepatic cytochrome P-450 monooxygenase system of rats pretreated with saline phenobarbitone (PB) and beta-naphthoflavone (BNF). Br inhibited ethoxyresorufin O-dealkylase (EROD) activity in liver microsomes of rats pretreated with saline and PB but not in BNF pretreated animals. Maximum inhibition of EROD activity by Br in the microsomes of saline and PB pretreated rats were 50%-60% of the control. In contrast, a dual effect was observed on aminopyrine N-demethylase activity (APD) by Br in microsomes of saline, PB and BNF pretreated rats. At a low concentration (25 microM), Br inhibited the activity of APD to a similar extent in all pretreatment groups; however, with higher concentrations of Br (50 microM to 300 microM), enhancement of APD activity was observed. Br (300 microM) increased the APD activity to 2-3 times the control level in microsomes of rats pretreated with saline, PB or BNF. Spectral studies revealed a Type II binding of Br to cytochrome P-450 from microsomes of saline and PB pretreated rats. A reverse type I binding was observed for BNF induced microsomes. In addition, Br also enhanced NADPH cytochrome c (P-450) reductase activity to a similar extent in all pretreatment groups. These results suggest that the inhibition of EROD activity may be due to direct binding by Br to certain isozymes of cytochrome P-450 and that the enhancing effect of Br on APD activity may be in part due to the activation of the NADPH cytochrome c reductase component of the cytochrome P-450 monooxygenase system. 相似文献
195.
Tun Li Myung G. Lee Win L. Chiou 《Journal of pharmacokinetics and pharmacodynamics》1986,14(5):495-509
Effects of differences in the rate and composition of intravenous fluid replacement for urine loss on the pharmacokinetics and pharmacodynamics of furosemide were evaluated using the dog as a model animal. Each of six dogs received 8-hr constant intravenous infusion of 20 mg (15 mg used in one dog) of furosemide with 0% replacement (treatment I), 50% replacement (treatment II), and 100% replacement (treatment III) with lactated Ringer's solution, as well as with 100% replacement with 5% dextrose in water (treatment IV). Most pharmacokinetic parameters, such as plasma clearance, steady-state volume of distribution, mean residence time, and terminal half-life, were essentially the same in all four treatments. Renal clearances and urinary excretion rates of the drug in treatments II–IVwere essentially the same, but about 20% higher than those in treatment I.In spite of the similarities in kinetic properties, diuretic and/or natriuretic effects from furosemide were markedly different among the four treatments. For example, mean 10-hr urine outputs were 646, 1046, 3156, and 1976 ml and mean 10-hr sodium excretions were 87.0, 142, 383, and 97.2 mmole for treatments I–IV,respectively. Except for treatment III,diuresis and/or natriuresis were found to be time-dependent, generally decreasing with time until reaching a low plateau during later hours of infusion. The present findings also showed that (1)no fluid replacement and 100% replacement with 5% dextrose solution both produced the same degree of severe acute tolerance in natriuresis, indicating the insignificance of water compensation in tolerance development; (2)in treatment II,where neutral sodium balance was achieved, the development of acute tolerance in diuresis and natriuresis can mainly be attributed to negative water balance under this special condition; (3)at steady state the hourly diuresis and natriuresis could differ up to about ten times between treatments. Some implications for the kinetic/dynamic relationship or modeling, in the clinical use, and in the bioequivalence evaluation of dosage forms are discussed. 相似文献
196.
Ute Bültmann Renée-Louise Franche Sheilah Hogg-Johnson Pierre Côté Hyunmi Lee Colette Severin Marjan Vidmar Nancy Carnide 《Quality of life research》2007,16(7):1167-1178
BACKGROUND: The purpose of this study was to describe the health status and work limitations in injured workers with musculoskeletal disorders at 1 month post-injury, stratified by return-to-work status, and to document their return-to-work trajectories 6 months post-injury. METHODS: A sample of 632 workers with a back or upper extremity musculoskeletal disorder, who filed a Workplace Safety and Insurance Board lost-time claim injury, participated in this prospective study. Participants were assessed at baseline (1 month post-injury) and at 6 months follow-up. RESULTS: One month post-injury, poor physical health, high levels of depressive symptoms and high work limitations are prevalent in workers, including in those with a sustained first return to work. Workers with a sustained first return to work report a better health status and fewer work limitations than those who experienced a recurrence of work absence or who never returned to work. Six months post-injury, the rate of recurrence of work absence in the trajectories of injured workers who have made at least one return to work attempt is high (38%), including the rate for workers with an initial sustained first return to work (27%). CONCLUSIONS: There are return-to-work status specific health outcomes in injured workers. A sustained first return to work is not equivalent to a complete recovery from musculoskeletal disorders. 相似文献
197.
Sumei Ren Paul McNamara Pernilla Royster Jae Lee Surinderjit S. Saluja David Koharski Sharon Hendershot Van Truong 《Journal of labelled compounds & radiopharmaceuticals》2007,50(7):643-648
1‐Benzyl‐4‐hydroxy[2‐14C]piperidine, a useful intermediate in labeled compound synthesis, was prepared from [14C]formaldehyde in high yield. The distribution pattern of 14C in the product is consistent with a mechanism involving reversible iminium ion formation and rapid equilibration of the iminium ion through a cationic aza‐Cope rearrangement. These steps precede the rate‐determining intramolecular cyclization step. SCH 351125 is a potent, selective CCR5 receptor antagonist with potential as a treatment for HIV infection. [14C]SCH 351125, required for metabolism studies, was prepared from 1‐benzyl‐4‐hydroxy[2‐14C]piperidine in six steps. [14C]SCH 351125 is a mixture of four atropisomers. Preparation of [14C]SCH 351125 besylate salt of the desired atropisomer pair is also described. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
198.
199.
Y J Lee 《Drugs under experimental and clinical research》1986,12(1-3):57-71
Sixty-seven recent phase II studies are reviewed with respect to their design, conduct and analysis. The review shows that in the majority of studies: (i) eligibility criteria are not clearly defined; (ii) no statistical method is applied in interpreting the results; (iii) not all the patients are considered evaluable. Negative conclusions are drawn from two-thirds of the studies. Very few studies give any statistical rationales for their design, and only nine studies are randomized studies. A review of all 17 phase II studies in breast cancer, reported in Cancer Treatment Reports between 1981 and 1983, shows that: (i) all the studies with 20 or more patients are negative; (ii) all the inconclusive studies are of small size; (iii) the distribution of patients according to prior chemotherapy is not comparable or the terminology used for prior therapy is not uniform. Review of all 19 studies in colorectal cancer, reported in Cancer Treatment Reports between 1981 and 1983, reveals, in addition to the above problems, that the 20% response rate to 5-FU in previously untreated patients is not supported. Proposals are made to improve the design, conduct and analysis of phase II studies. Methods for analysing phase II study data are reviewed and two-stage designs appropriate for phase II trials in cancer are discussed. 相似文献
200.
Reversible electroencephalogram changes associated with administration of baclofen in a quadriplegic patient: case report 总被引:2,自引:0,他引:2
We present the case of a spastic quadriplegic who developed mental symptoms which resolved when his Baclofen was discontinued. Of interest was the presence of EEG abnormalities similar to those described in cats receiving this drug. These abnormalities, previously unreported in humans, resolved upon discontinuing Baclofen therapy. 相似文献