全文获取类型
收费全文 | 25087篇 |
免费 | 1638篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 202篇 |
儿科学 | 877篇 |
妇产科学 | 702篇 |
基础医学 | 3089篇 |
口腔科学 | 260篇 |
临床医学 | 3934篇 |
内科学 | 4521篇 |
皮肤病学 | 297篇 |
神经病学 | 2482篇 |
特种医学 | 524篇 |
外科学 | 2049篇 |
综合类 | 277篇 |
一般理论 | 64篇 |
预防医学 | 3673篇 |
眼科学 | 334篇 |
药学 | 1440篇 |
1篇 | |
中国医学 | 26篇 |
肿瘤学 | 2020篇 |
出版年
2023年 | 96篇 |
2022年 | 155篇 |
2021年 | 429篇 |
2020年 | 290篇 |
2019年 | 457篇 |
2018年 | 549篇 |
2017年 | 427篇 |
2016年 | 440篇 |
2015年 | 493篇 |
2014年 | 776篇 |
2013年 | 1237篇 |
2012年 | 1794篇 |
2011年 | 1870篇 |
2010年 | 1019篇 |
2009年 | 889篇 |
2008年 | 1722篇 |
2007年 | 1814篇 |
2006年 | 1802篇 |
2005年 | 1841篇 |
2004年 | 1760篇 |
2003年 | 1668篇 |
2002年 | 1538篇 |
2001年 | 172篇 |
2000年 | 120篇 |
1999年 | 234篇 |
1998年 | 335篇 |
1997年 | 239篇 |
1996年 | 234篇 |
1995年 | 222篇 |
1994年 | 189篇 |
1993年 | 181篇 |
1992年 | 115篇 |
1991年 | 104篇 |
1990年 | 83篇 |
1989年 | 95篇 |
1988年 | 81篇 |
1987年 | 74篇 |
1986年 | 76篇 |
1985年 | 83篇 |
1984年 | 115篇 |
1983年 | 114篇 |
1982年 | 134篇 |
1981年 | 121篇 |
1980年 | 113篇 |
1979年 | 58篇 |
1978年 | 64篇 |
1977年 | 63篇 |
1976年 | 47篇 |
1975年 | 43篇 |
1974年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Michael C Graves Milan Fiala Lu Anne V Dinglasan Nancy Q Liu James Sayre Francesco Chiappelli Cees van Kooten Harry V Vinters 《Amyotrophic lateral sclerosis and other motor neuron disorders》2004,5(4):213-219
Recent studies have shown inflammatory markers in affected neural tissues of amyotrophic lateral sclerosis (ALS) patients. We examined immunocytochemically spinal cord tissues of six patients with ALS, two with corticospinal tract degeneration secondary to cerebral infarcts and three control subjects without neuropathologic abnormalities. ALS spinal cords had dense macrophage infiltration (one log greater than control spinal cords) involving the white and gray matter, with heaviest infiltration of lateral and ventral columns and, in one patient, prefrontal gyrus and the occipital lobes of the brain. Macrophages in ALS spinal cord showed strong expression of cyclooxygenase-2 (COX-2) (one log greater than control tissues) and inducible nitric oxide synthase. In the gray matter, macrophages surrounded and appeared to phagocytize neurons (NeuN-positive) that appeared to be dying. Vessels showed damage to the tight junction protein ZO-1 in relation to perivascular CD40 receptor-positive macrophages and CD40 ligand-positive T lymphocytes. ALS spinal cords, but not control cords, were sparsely infiltrated with mast cells. In control cases with corticospinal tract degeneration following hemispheric cerebral infarction, macrophage infiltration of the white matter was COX-2-negative and restricted to lateral and anterior corticospinal tracts. Our data suggest that inflammation in ALS spinal cord and cortex is based on innate immune responses by macrophages and mast cells and adaptive immune responses by T cells. 相似文献
103.
Joseph R. Holtman Jr. Nancy C. Anastasi Wesley P. Norman Kenneth L. Dretchen 《Brain research》1986,362(2)
The effect of electrical and chemical (l-glutamate) stimulation of the raphe obscurus on phrenic nerve activity was examined in the cat. Phrenic nerve activity was recorded from a C5 nerve root in anesthetized, paralyzed and artificially ventilated cats. Neural discharge was quantitated by integrating the phrenic nerve activity. The respiratory frequency was determined from the integrated nerve signal. Focal electrical stimulation (18–144 μA; 5–40 Hz; 100 μs pulse duration) resulted in significant (P < 0.05) increases in both integrated phrenic nerve (IPN) amplitude and respiratory frequency. These changes were dependent upon current intensity and frequency of stimulation. The largest increases in IPN amplitude and respiratory frequency were47 ± 17%and146 ± 8%, respectively. To insure that the changes in integrated phrenic nerve activity (IPNA) were the result of stimulation of cell bodies and not axons of passage,l-glutamate (100, 200 nmol) was microinjected (100 nl) into the raphe obscurus. Significant (P < 0.05) dose-related changes occurred in integrated phrenic nerve amplitude with an increase of44 ± 13% at 100 nmol and80 ± 13% at 200 nmoll-glutamate. No significant increase in respiratory frequency was observed withl-glutamate microinjection. The results suggest that the raphe obscurus may be involved in respiratory control. 相似文献
104.
105.
Nurse-midwifery students face multiple stressors in their educational experience. Strategies to resolve stress and promote adaptation to the new role are examined and measures used to promote students' adaptation to the educational experience are described. 相似文献
106.
107.
Shibahara Hiroaki; Shigeta Minoru; Inoue Miyuki; Hasegawa Akiko; Koyama Koji; Alexander Nancy J.; Isojima Sinzo 《Human reproduction (Oxford, England)》1996,11(12):2595-2599
The blocking effects of complement-dependent sperm immobilizingantibodies in the sera of infertile women and monoclonal antispermantibodies against humans and mice on fertilization were investigated.The hemizona assay (HZA) and sperm penetration assay (SPA) wereused to study the inhibitory effects of sera from 22 infertilepatients positive for sperm immobilizing antibodies. Use ofthese tests allowed us to differentiate whether the antibodyblocked spermzona pellucida tight binding and/or spermpenetration into the ooplasm. The zona pellucida penetrationassay (ZPA) was also used to study the effects of four monoclonalantibodies (mAbs) on human sperm penetration into the zona pellucida.Seven mAbs against murine spermatozoa were tested for theirinhibitory effects on in-vitro fertilization (IVF) and HZA inmice. Of 22 patient sera with sperm immobilizing antibodies,21 (95.5%) inhibited HZA attachment and penetration, whereasthis did not occur in any of 13 patient sera without these antibodies.However, 19 of 22 (86.4%) patient sera with sperm immobilizingantibodies and eight of 13 (61.5%) patient sera without theseantibodies inhibited the SPA. Two (2C6, 1G12) of four mAbs againsthuman spermatozoa showed strong inhibitory effects in all theassays (HZA, ZPA and SPA). One mAb (3B10) did not inhibit HZAbut blocked ZPA and SPA. Another mAb (H6-3C4) seemed to haveno inhibitory effects on fertilization. Two (Vx 5 and Vx 8)of seven mAbs against murine spermatozoa inhibited IVF in micebut did not block mouse HZA. These findings suggest that antispermantibodies block fertilization at specific stages. Some of themmay inhibit sperm capacitation and thus prevent all processesof fertilization that follow. Some other antibodies may notaffect capacitation and sperm binding to zona pellucida butinhibit the acrosome reaction, followed by the blocking of spermpenetration through zona pellucida and ooplasm. 相似文献
108.
Michael Horowitz Phillip Purdy Hal Unwin George Carstens Ralph Greenlee Joe Hise Tom Kopitnik Hunt Batjer Nancy Rollins Duke Samson 《Annals of neurology》1995,38(1):58-67
Thrombosis of the cerebral dural venous sinuses, cortical draining veins, and deep cerebral veins is a rare clinical finding. Because of its low incidence and multiple etiologies, the optimum therapy for this condition will only be elucidated by a multicenter, randomized prospective study. At our institution, we favor early and aggressive management of cerebral venous sinus thrombosis with transfemoral, venous intradural infusions of the fibrinolytic agent urokinase. To date, treatment of only 13 patients using this technique has been reported in the English literature. This report adds 12 more such treated patients. Despite the presence of preinfusion infarcts in 5 patients, four of which were hemorrhagic, we incurred no major therapeutic morbidity. Functional sinus patency was achieved in 11 of 12 patients, with our only true failure occurring in an individual with symptoms of at least 2 months' duration. Good to excellent clinical outcome was achieved in 10 of 11 patients (one newborn had inadequate follow-up). 相似文献
109.
Dr. Nancy E. Winslade Pharm.D. Dr. Linda. M. Strand Ph.D. Dr. John. A. Pugsley Pharm.D. Dr. Don. G. Perrier Ph.D. 《Pharmacotherapy》1996,16(5):889-898
Pharmaceutical care is a concept outlining the responsibilities of individual pharmacists to individual patients. Although widely accepted on a philosophical basis, there is a lack of comprehensive information about the functions and responsibilities pharmacists undertake when providing pharmaceutical care. Pharmacy educators and practitioners at the faculty of pharmacy, University of Toronto, developed and informally tested a process that details the practice functions required of pharmacists when providing pharmaceutical care as originally defined. 相似文献
110.
Helen E. Pearson Donna L. Smith-Harrison Nancy K. Rosenblatt Bertram R. Payne 《Experimental neurology》1993,119(2)
The short-term metabolic response of immature retinal ganglion cells to destruction of their target cells in the dorsal lateral geniculate nucleus (dLGN) was assessed in newborn cats. Retrograde degeneration of virtually all dLGN cells was induced by ablation of the 13 contiguous areas of visual cortex on the day of birth. The metabolic response of retinal ganglion cells to this loss of target cells in dLGN was determined by exposing the ganglion cell layer to tritiated uridine, a precursor of RNA. Control measurements were made from unoperated littermates. Following sectioning and processing of the retinae from both groups of kittens for autoradiography, silver grain densities overlying the cellular profiles in the ganglion cell layer were calculated. These calculations revealed levels of uridine incorporation at Postnatal Day 4 in both groups of kittens significantly higher than at either Postnatal Day 2 or 7, but no significant differences between the two groups on any day examined. These results show that the level of RNA synthesis in retinal ganglion cells increases temporarily during the first postnatal week and that this synthesis is unaffected by the death of target cells in the dLGN. The temporary increase may be related to the establishment of synaptic connections on retinal ganglion cells by their afferent bipolar and amacrine neurons in the inner nuclear layer. 相似文献