全文获取类型
收费全文 | 1151篇 |
免费 | 55篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 6篇 |
妇产科学 | 5篇 |
基础医学 | 158篇 |
口腔科学 | 64篇 |
临床医学 | 50篇 |
内科学 | 124篇 |
皮肤病学 | 44篇 |
神经病学 | 82篇 |
特种医学 | 42篇 |
外科学 | 36篇 |
综合类 | 119篇 |
预防医学 | 80篇 |
眼科学 | 226篇 |
药学 | 86篇 |
1篇 | |
中国医学 | 13篇 |
肿瘤学 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 31篇 |
2021年 | 33篇 |
2020年 | 36篇 |
2019年 | 37篇 |
2018年 | 37篇 |
2017年 | 28篇 |
2016年 | 30篇 |
2015年 | 29篇 |
2014年 | 52篇 |
2013年 | 82篇 |
2012年 | 71篇 |
2011年 | 62篇 |
2010年 | 47篇 |
2009年 | 58篇 |
2008年 | 55篇 |
2007年 | 55篇 |
2006年 | 51篇 |
2005年 | 44篇 |
2004年 | 44篇 |
2003年 | 25篇 |
2002年 | 35篇 |
2001年 | 19篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1228条查询结果,搜索用时 15 毫秒
1.
2.
3.
Edda TÖPFER-PETERSEN Johanna AUERBECK Angelika WEISS A.E. FRIESS and W.-B. SCHILL 《Andrologia》1986,18(3):237-251
An antiserum to the purified porcine outer acrosomal membrane (OAM) was raised in female Balb/c mice and was characterized by means of an indirect ELISA. The hyperimmune serum reacted selectively with the acrosomal cap of the sperm head and showed an extremely good cross reactivity with bull and human spermatozoa when assayed by indirect immunofluorescence. Immunoelectron microscopy using the protein A-gold method further confirmed the specificity of the anti-OAM-antiserum for the OAM. In an effort to identify the OAM antigens recognized by the hyperimmune serum and to analyse the extent of cross reactivity on a molecular level, the SDS-extractable proteins were separated by SDS-PAGE, transblotted and immunoprinted using an 125J-conjugated anti-mouse-antibody. To facilitate functional and structural analysis of distinct OAM-proteins monoclonal antibodies were generated by hybridization of mouse myeloma cells with the splenocytes of female Balb/c mice immunized with the purified OAM. One fusion resulted in about 100 anti-OAM-antibodies secreting hybridoma cultures, of which about 30% showed cross reaction with human and bull spermatozoa. Four stable cell lines were selected for this study secreting antibodies directed against the outer acrosomal membrane of boar spermatozoa. Whereas the polyclonal immune mouse serum stained the entire acrosomal cap, the four hybridoma antibodies generated a patch-work-like immunofluorescence pattern over the acrosome. HPLC-ELISA of the solubilized OAM revealed first information on the nature of the corresponding membrane antigen. 相似文献
4.
Chemically distinct rat olivocochlear neurons. 总被引:6,自引:0,他引:6
We have produced a neurochemical map of the cell bodies of origin of the cochlear efferent terminals in rat by combining glutamic acid decarboxylase (GAD), choline acetyltransferase (ChAT), or calcitonin gene-related peptide (CGRP) immunocytochemistry with retrograde transport of horseradish peroxidase. The locations of cochlear efferent cell bodies are in general agreement with the medial and lateral systems described by White and Warr (J. Comp. Neurol. 219:203-214, 1983) with some minor modifications. The lateral system consists of at least two pools of chemically distinct neurons located within the lateral superior olive (LSO) ipsilateral to the injected cochlea. One pool immunostains with an antibody to GAD while the other immunostains with antibodies to ChAT and to CGRP. The medial efferent system consists of periolivary neurons that are almost exclusively large and ChAT-positive but CGRP-negative. They are located both ipsilateral and contralateral to the cochlea they project to. There are a few GAD-positive small neurons in the medioventral and rostral periolivary regions that project ipsilaterally, but these may prove tobe ectopic neurons. The ipsilateral lateroventral periolivary region (LVPO) contains some efferent neurons, all of which are ChAT-positive but CGRP-negative. Additional cochlear efferent neurons, some of which are ChAT-positive and others GAD-positive, are present within and immediately dorsal to the fiber capsule surrounding the medial limb, and to a lesser extent the lateral limb, of the ipsilateral LSO. Not all GAD-positive or ChAT-positive olivary cells project to the cochlea. We have complemented the results in the brainstem by demonstrating two immunocytochemically distinct populations of efferent terminals in the cochlea simultaneously, one CGRP-positive and the other GAD-positive. Approximately equal numbers of boutons immunoreactive for both markers are present beneath inner hair cells throughout the entire length of the cochlea. Surprisingly high numbers of GAD-positive and CGRP-positive boutons are also present on outer hair cells, with each class having its spatially and morphologically distinct features. The lack of CGRP-positive periolivary cells that are retrogradely labeled by cochlear injections of HRP suggests that the lateral olivocochlear system sends projections to outer hair cells. Our results raise questions about species differences in the organization of targets of the lateral and medial olivocochlear systems. 相似文献
5.
Jhoji Tanabe Hirohiko Nakazato Hisayoshi Tanabe Hidetoshi Hanasaki Kazuo Kawasaki Daizo Yonemura 《Documenta ophthalmologica. Advances in ophthalmology》1986,63(2):165-171
The spectral response curve (amplitude versus wavelength) of the R2 of the early receptor potential (ERP) was studied in normal, protan, and deutan subjects. The R2 amplitude peaked at 520nm in most normal subjects. The R2 at long wavelengths was smaller than normal in protans and larger than normal in deutans when the maximum amplitudes were normalized to 100% at the peak. The ratio of the R2 amplitude at 460 nm to that at 600 nm clearly differed between protans and deutans. The ERP and the rapid off-response, which is mainly due to the cessation of the late receptor potential, were recorded in the same subjects. The ratio of the sensitivity of the rapid off-response at 500 nm to that at 600 nm was correlated with the ratio of the R2 amplitude at 460 nm to that at 600nm (correlation coefficient, 0.823, p < 0.001). This study, in conjunction with our previous study, indicates that the abnormality is in the outer segments of the cones in protans and deutans. 相似文献
6.
R. HENKEL T. STALF N. MERTENS W. MISKA W.-B. SCHILL 《International journal of andrology》1994,17(2):68-73
The outer dense fibres are accessory fibres in the spermatozoon. They represent up to 30% of the protein portion in human spermatozoa and are involved in sperm progressive motility. If outer dense fibres are missing or developed poorly, spermatozoa are only locally motile. For isolation of the outer dense fibres, human spermatozoa were sonicated at 25 kHz and the flagella were separated by density gradient centrifugation in Percoll. Thereafter, membranes and fibrous sheath were dissolved under reducing conditions in the cationic detergent cetyltrimethylammonium bromide for 30, 60 and 90 min, respectively. The isolation steps were monitored by phase contrast microscopy and electron microscopy. After SDS-polyacrylamide gel electrophoresis and silver staining of isolated outer dense fibres, two protein bands at 55 and 67 kDa could be detected. By means of rhodamine B staining, no phosphorus could be detected in the outer dense fibre proteins. 相似文献
7.
Gary N. Holland 《International ophthalmology》1994,18(3):163-165
The progressive outer retinal necrosis (PORN) syndrome is a recently described clinical variant of necrotizing herpetic retinopathy in patients with the acquired immunodeficiency syndrome (AIDS). It is caused by varicellazoster virus infection of the retina. Its course and clinical features distinguish it from the acute retinal necrosis syndrome and CMV retinopathy. Early disease is characterized by multifocal deep retinal opacification. Lesions rapidly coalesce and progress to total retinal necrosis over a short period of time. Despite aggressive therapy with intravenous antivirial drugs, prognosis is poor; disease progression and/or recurrence is common, and the majority of patients develop no light perception vision. Total retinal detachments are common. Prophylaxis against retinal detachment using laser retinopexy has not been useful in most cases. PORN syndrome is an uncommon, but devastating complication of AIDS. 相似文献
8.
A restricted field of view (rFOV) approach for imaging a dynamic time series of volumes of limited spatial extent within a larger subject is described. The shorter readout with rFOV-MRI can be exploited to either limit image artifacts or increase spatial resolution. To accomplish rFOV imaging of a multislice volume for a dynamic series, an outer volume suppression (OVS) preparation that saturates signal external to a cylinder through the subject is followed by slice-selective excitation and a spiral readout. The pass- and stopband efficiencies of the OVS in an agar gel phantom were 97% (+/-1.5%) and 3% (+/-1%), respectively. Profiles of the temporal signal-to-noise ratio (SNR) were measured in a phantom and an adult brain. The rFOV sequence reduced distortions from off-resonance signal and T2*-induced blurring compared to a conventional sequence. Sequence utility is demonstrated for high-resolution rFOV functional MRI (fMRI) in the visual cortex. The rFOV sequence may prove to be useful for other multislice dynamic and high-resolution imaging applications. 相似文献
9.
以军团菌DNA为模板,PCR扩增获得军团菌主要外膜蛋白基因(Major outer membrane protein gene,ompS),与原核表达质粒pUC18定向重组,构建重组质粒,转化大肠杆菌BL21,并用限制性酶酶切分析、聚合酶链式反应、核酸序列分析、十二烷基磺酸钠-聚丙烯酰胺凝胶电泳、Western印迹进行鉴定。实验结果表明我们扩增出了军团菌914bp的ompS基因,成功构建了重组质粒pLPompS,并在原核系统中得到了表达。 相似文献
10.
Franz -X. Beck Masayoshi Sone Adolf Dörge Klaus Thurau 《Pflügers Archiv : European journal of physiology》1992,422(3):233-238
Sodium absorption in distal tubule segments was stimulated by increasing the distal delivery via infusion of hypertonic saline. In these animals, and in control rats, electrolyte concentrations in thick ascending limb cells, light and dark cells of the collecting duct in the outer and inner stripe of the outer medulla and in cells of the proximal straight tubule (outer stripe only) were studied. The measurements were performed by electron microprobe analysis of freeze-dried cryosections of the outer medulla. In addition, organic osmolytes (glycerophosphorylcholine, betaine and myo-inositol) were measured by high performance liquid chromatography in cortex and outer medulla. Augmented delivery of sodium chloride to the distal tubule was associated with increased sodium concentrations of thick ascending limb cells both in the outer and inner stripe and of medullary collecting duct light and dark cells in the outer stripe. While the sum of organic osmolyte concentrations was 28% higher in the outer medulla of the salt-loaded animals compared with controls, this value was unchanged in the renal cortex. These findings indicate that the primary event underlying stimulation of sodium absorption along the thick ascending limb during increased distal sodium delivery is enhanced entry of sodium across the apical cell membrane. This would be expected to lead to higher cell sodium concentrations and stimulation of basolateral active Na-K-exchange. The enhanced transport activity of outer medullary tubules may be associated with increased interstitial tonicities and intracellular retention of organic osmolytes. 相似文献