全文获取类型
收费全文 | 2150篇 |
免费 | 202篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 76篇 |
妇产科学 | 41篇 |
基础医学 | 305篇 |
口腔科学 | 29篇 |
临床医学 | 238篇 |
内科学 | 484篇 |
皮肤病学 | 32篇 |
神经病学 | 150篇 |
特种医学 | 47篇 |
外科学 | 329篇 |
综合类 | 48篇 |
一般理论 | 1篇 |
预防医学 | 207篇 |
眼科学 | 16篇 |
药学 | 197篇 |
中国医学 | 1篇 |
肿瘤学 | 106篇 |
出版年
2023年 | 15篇 |
2021年 | 44篇 |
2020年 | 30篇 |
2019年 | 31篇 |
2018年 | 49篇 |
2017年 | 40篇 |
2016年 | 25篇 |
2015年 | 38篇 |
2014年 | 56篇 |
2013年 | 81篇 |
2012年 | 102篇 |
2011年 | 125篇 |
2010年 | 58篇 |
2009年 | 61篇 |
2008年 | 107篇 |
2007年 | 115篇 |
2006年 | 94篇 |
2005年 | 88篇 |
2004年 | 102篇 |
2003年 | 72篇 |
2002年 | 84篇 |
2001年 | 45篇 |
2000年 | 71篇 |
1999年 | 60篇 |
1998年 | 21篇 |
1997年 | 29篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 52篇 |
1991年 | 39篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 34篇 |
1987年 | 38篇 |
1986年 | 36篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 18篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 21篇 |
1974年 | 25篇 |
1973年 | 17篇 |
1972年 | 16篇 |
1969年 | 14篇 |
1968年 | 13篇 |
排序方式: 共有2355条查询结果,搜索用时 0 毫秒
11.
12.
Plasmids carrying type I or II sulfonamide-resistance (Sur) genes were evaluated for their effect on synergy between trimethoprim (Tmp) and sulfamethoxyzole (Smx) in E. coli. Strain J53 containing each of three plasmids (R1, pSa, and R388) with the type I Sur gene displayed a synergistic response to Tmp/Smx; strain LE392 containing a plasmid (RSF1010) with the type II Sur gene displayed no synergy. The difference in synergy between type I and type II Sur genes might be explained by the difference in amount of resistant enzyme produced. 相似文献
13.
14.
V M Walley C F Coates J J Gilbert G H Valentine E M Davies 《American journal of medical genetics》1983,14(3):445-452
We describe a baby with external and internal anomalies of the Majewski form of the short rib-polydactyly (SRP) syndromes. Previously unreported abnormal vertebral bodies, delayed ossification of the sternum and fibulae, and a diencephalic hamartoma are noted. These abnormalities and minimal histologic abnormality at the chondro-osseous junction suggest that this syndrome may be heterogeneous or more variable than previously known. 相似文献
15.
Development of Duchenne-type cardiomyopathy. Morphologic studies in a canine model. 总被引:1,自引:0,他引:1 下载免费PDF全文
The development of cardiac lesions was studied in xmd dogs aged from 1 day to 6 years. Cardiac lesions were not present in dystrophic dogs up to 3 months of age. Foci of mineralization were first seen at 6.5 months. A 1-year-old dog had foci of myocyte hypercontraction. Linear and anastomosing fibrosis was present in all dogs 1 year of age or older, most prominently and most consistently within the subepicardial region of the left ventricular (LV) free wall, the LV papillary muscles, and the right ventricular (RV) aspect of the septum. Ultrastructurally, endomysial fibrosis, decreased myofibrillar density, and prominence of mitochondria were consistent features. Severe degenerative changes were present in two dogs and included prominent intracytoplasmic myelin figures, lipid droplets, and lipofuscin. Immunocytochemical studies of an affected dog confirmed the absence of dystrophin in LV myocardium. Characteristic late-onset cardiac lesions, similar to those occurring in Duchenne dystrophy, are a consistent feature of canine X-linked muscular dystrophy (CXMD). 相似文献
16.
Detection of N-myc gene amplification by fluorescence in situ hybridization. Diagnostic utility for neuroblastoma. 总被引:4,自引:1,他引:4 下载免费PDF全文
D. N. Shapiro M. B. Valentine S. T. Rowe A. E. Sinclair J. E. Sublett W. M. Roberts A. T. Look 《The American journal of pathology》1993,142(5):1339-1346
We assessed fluorescence in situ hybridization (FISH) as an alternative to Southern blot analysis for determination of N-myc gene amplification in neuroblastoma. In the 44 pediatric solid tumor cell lines examined (20 neuroblastomas), the mean number of N-myc copies determined by FISH correlated closely with Southern blot results. There was wide intercellular variability in gene copy number in tumors that had evidence of amplification; however, tumors judged to be non-amplified completely lacked any cells with high N-myc copy number. FISH provided reliable estimates of N-myc amplification in 12 clinical samples even when the percentage of tumor was low. The other advantages of FISH over Southern blot analysis were speed and technical simplicity, ability to discern heterogeneous gene amplification among tumor cells in the same specimen, and capacity to determine the source of the amplified N-myc signal, whether extrachromosomal double-minute chromosomes, expanded intrachromosomal regions, or chromosome 2 aneuploidy. We conclude that FISH would refine the analysis of N-myc amplification in neuroblastoma and thus improve the assignment of patients to prognostic groups based on this unfavorable risk factor. 相似文献
17.
Characteristics of bovine alveolar macrophage elastase 总被引:4,自引:0,他引:4
Lavage of isolated bovine lung lobes was used to retrieve pulmonary alveolar macrophages (PAM). Nominal yields of 72 million viable PAM were routinely obtained using 500 ml of calcium- and magnesium-free phosphate-buffered saline. Bovine PAM readily attached to glass coverslips and within 24 hours, provided cell monolayers consisting exclusively of macrophages. Bovine PAM synthesized and secreted a calcium-dependent elastase in serum-free media. Optimal proteolytic activity using a radiolabeled elastin substrate was observed at pH 7.6. The elastase was insensitive to synthetic peptide chloromethyl ketone elastase inhibitors and to the serine protease inhibitor, phenylmethylsulfonyl fluoride. Enzyme activity, however, was effectively inhibited by the metal chelator, ethylenediaminetetraacetic acid, or suppressed by inhibition of protein synthesis with cycloheximide. 相似文献
18.
19.
20.
Epilepsy is a family of neurological disorders that result in seizure activity that is characterized by transient hypersynchronous activation of a large population of neurons. In animal models, focal tetanic electrical stimulation of sufficient duration and intensity, can elicit epileptiform activity, that if repeated results in progressive intensification of seizure activity known as kindling. Kindling serves as a model of partial as well as secondarily generalized temporal lobe epilepsy. We utilized hippocampal kindling to provide a means of evaluating the effect of sensory stimulation on the duration and severity of the induced seizure activity. Sensory stimuli targeted either the olfactory, auditory or somatosensory systems in an attempt to retard or suppress seizure activity. To that end, rats were chronically implanted with electrodes in the CA1 region of dorsal hippocampus and kindled once daily until the seizure behaviour was fully generalized. Kindling stimulation consisted of daily application of 1-s trains of biphasic square wave pulses applied at a frequency of 60Hz, at the afterdischarge (AD) threshold. Sensory stimulation was applied 6-8s after the kindling stimulation every third day. One group of rats received a different sensory stimulus (novel) every third day, while another group was presented with the same sensory stimulus (repeated) every third day. Kindling stimulation applied to the dorsal hippocampus resulted in progression of the AD characteristics and seizure behavior, which typically developed very slowly in the early stages. The application of both the novel and repeated sensory stimulation during partial seizures (stages 1 and 2) resulted in a reduction in the seizure severity but not in the afterdischarge duration. Sensory stimulation delivered during secondarily generalized seizures (stages 4 and 5) failed to affect either parameter. 相似文献