全文获取类型
收费全文 | 9923篇 |
免费 | 496篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 108篇 |
儿科学 | 194篇 |
妇产科学 | 199篇 |
基础医学 | 1565篇 |
口腔科学 | 189篇 |
临床医学 | 616篇 |
内科学 | 2277篇 |
皮肤病学 | 255篇 |
神经病学 | 635篇 |
特种医学 | 385篇 |
外科学 | 1621篇 |
综合类 | 29篇 |
预防医学 | 374篇 |
眼科学 | 170篇 |
药学 | 706篇 |
中国医学 | 10篇 |
肿瘤学 | 1141篇 |
出版年
2023年 | 53篇 |
2022年 | 93篇 |
2021年 | 152篇 |
2020年 | 89篇 |
2019年 | 121篇 |
2018年 | 131篇 |
2017年 | 115篇 |
2016年 | 172篇 |
2015年 | 168篇 |
2014年 | 212篇 |
2013年 | 278篇 |
2012年 | 441篇 |
2011年 | 478篇 |
2010年 | 256篇 |
2009年 | 258篇 |
2008年 | 446篇 |
2007年 | 495篇 |
2006年 | 522篇 |
2005年 | 494篇 |
2004年 | 497篇 |
2003年 | 496篇 |
2002年 | 478篇 |
2001年 | 359篇 |
2000年 | 355篇 |
1999年 | 334篇 |
1998年 | 169篇 |
1997年 | 128篇 |
1996年 | 91篇 |
1995年 | 85篇 |
1994年 | 68篇 |
1993年 | 74篇 |
1992年 | 219篇 |
1991年 | 174篇 |
1990年 | 198篇 |
1989年 | 209篇 |
1988年 | 210篇 |
1987年 | 171篇 |
1986年 | 148篇 |
1985年 | 137篇 |
1984年 | 112篇 |
1983年 | 90篇 |
1982年 | 44篇 |
1979年 | 60篇 |
1978年 | 38篇 |
1977年 | 45篇 |
1974年 | 44篇 |
1973年 | 51篇 |
1972年 | 43篇 |
1970年 | 47篇 |
1968年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 60 毫秒
1.
Two-color flow cytometry was carried out to determine the correlation between cell-mediated immunity and the levels of proteinuria in 30 patients with membranous nephropathy. Lymphocyte subpopulations were measured by two-color flow cytometry using various monoclonal antibodies of the Leu series. Clinically, the patients were divided into four stages as follows: 1. untreated nephrotic stage, 2. prednisolone (PSL) treated nephrotic stage, 3. persistent proteinuric stage (incomplete remission, ICR) and 4. complete remission (CR). Two-color flow cytometry showed a significant decrease in Leu 2a+15+ (suppressor T) cells and relative increase in Leu 3a+8+ (suppressor inducer T) cells in the untreated nephrotic stage. The mean Leu 3a+8-/Leu 2a+15+ (helper/suppressor) cell ratio was normalized in the persistent proteinuric stage or complete remission after treatment with PSL. Patients with membranous nephropathy showed a significant elevation of Leu 2a+DR+ cells after treatment with PSL. The abnormalities of suppressor T cells and suppressor inducer T cells in the peripheral blood appear to reflect the levels of proteinuria in patients with membranous nephropathy. It was concluded that PSL might stimulate Leu 2a positive cells and then increase the number of Leu 2a+15+ cells in the peripheral blood of patients with membranous nephropathy. 相似文献
2.
3.
M Nakayama Y Takahashi H Itoh K Kamiya M Shiratsuchi G Otani 《The Journal of antibiotics》1989,42(11):1535-1540
Two antifungal antibiotics maniwamycins A and B were isolated from the culture broth of a strain of actinomycetes, which were classified as Streptomyces prasinopilosus. These antibiotics were isolated by resin absorption and extraction with EtOAc and purified by column chromatography. Both antibiotics were found to be new azoxy substances from their physico-chemical properties. They showed broad antifungal spectra. 相似文献
4.
K Nakayama Y Nemoto Y Inoue T Mochizuki S B Soares Jr K Ohata J Katsuyama Y Onoyama K Wakasa 《AJNR. American journal of neuroradiology》1997,18(2):331
Cranial malignant fibrous histiocytomas are rare tumors. Most are hypervascular, destructive masses that are similar to other malignant lesions and to malignant fibrous histiocytomas found elsewhere in the body. We describe a myxoid malignant fibrous histiocytoma of the temporal bone, possibly of dural origin, with features that more closely resembled a meningioma at CT, MR imaging, and angiography. 相似文献
5.
A 28-year-old woman developed numbness and weakness of the hands and arms when she was 8 months pregnant, and weakness worsened gradually. However, weakness started to spontaneously subside immediately after delivery and she felt almost recovered several hours later. But weakness and numbness recurred one week after delivery and she was admitted to our hospital. Neurological examination revealed moderate weakness and disturbance of the deep and cutaneous sensations in the upper and lower extremities, and marked decrease of the deep tendon reflexes. The upper extremities were more severely affected. Nerve conduction study showed marked decrease in the motor conduction velocities. Cerebrospinal fluid showed increase of protein without pleocytosis. Teased preparation of the biopsied sural nerve showed occasional internodal segments with thin myelination, indicating demyelination and remyelination. A diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy was made. Treatment with prednisolone markedly improved the weakness and hyporeflexia as well as the cerebrospinal fluid protein. Postpartum rapid remission may have been produced by rapid increase of endogenous steroid hormone in the blood by its massive excretion during delivery. 相似文献
6.
J T Chen Y Kurokawa K Nakayama K Saito K Sakamoto K Fukuda Y Hirai T Hamada I Fujimoto K Yamauchi 《Nippon Sanka Fujinka Gakkai zasshi》1987,39(5):815-822
Bismuth subnitrate (BSN), a bismuth compound medically used for antidiarrheics, was orally administered to see whether it can reduce CDDP nephrotoxicity or not. Thirteen patients aged 19 approximately 60 with ovarian cancer entered this BSN-CDDP trial. A total of thirty three courses of BSN-CDDP treatment was undergone. BSN was administered orally at a dose of 50 mg/kg for five days before CDDP therapy. CDDP was infused for two hours. No vigorous hydration or diuresis was performed. Only 2,000 ml of saline with 20 mEq per liter of KCl was given for post-hydration. The median dose of CDDP was 100 mg/m2. The renal toxicity of BSN-CDDP treatment was minimum. 82% of the courses at the sixth day after the treatment had creatinine clearance levels which were more than 80% of those before the treatment. But twenty-four hour NAG and beta 2-microglobulin excretion were significantly increased. Bone marrow suppression and gastrointestinal disturbance were commonly observed. The results of our study indicate that BSN pretreatment reduces the renal toxicity of CDDP to some extent. 相似文献
7.
Localization of ferritin using a pre-embedding diffusion technique and an indirect localization sequence has been made in 34 cases of human liver under normal and several pathological conditions. With light microscopic observation, positive immuno-staining for ferritin was demonstrated as diffuse deposits in the hepatocytes and Kupffer cells. Intensity of the positive immuno-staining for ferritin in these cells appeared to roughly coincide with serum ferritin levels of each patient, but showed no disease specificity, although hepatoma cells contained weak deposits or were negative from immuno-staining for ferritin. With electron microscopic studies, intracellular antigen was well preserved in the hepatocytes and Kupffer cells in most cases with the positive immuno-staining for ferritin being observed in cytosol and a few cisternae of rough endoplasmic reticulum. Content of the positive immuno-staining for ferritin differed considerably from one case to another and one cell to another even in the same case. There was no immuno-staining for ferritin in hemosiderin pigment, lysosome, most of rough endoplasmic reticulum, Golgi complexes, and nucleus in both cells. 相似文献
8.
Yasuomi Ouchi Teiji Nakayama Toshihiko Kanno Etsuji Yoshikawa Tomomi Shinke Tatsuo Torizuka 《Journal of cerebral blood flow and metabolism》2007,27(4):803-810
Differentiation of impaired gait seen in idiopathic normal pressure hydrocephalus (iNPH) from parkinsonian gait is sometimes a great challenge and important for future medication in the clinical setting. To investigate dopaminergic contribution to its pathophysiology, two aspects of the trans-synaptic dopamine functions in the striatal region in eight iNPH patients na?ve to dopaminergic drugs were examined using positron emission tomography with a presynaptic marker [11C]CFT ([11C]2-beta-carbomethoxy-3beta-(4-fluorophenyl) tropane) that binds to dopamine transporter and a postsynaptic marker [11C]raclopride that binds to D2 receptor. Quantitative values of binding potentials (BPs) for [11C]CFT and [11C]raclopride were compared between patients and eight age-matched healthy subjects. The BPs and magnetic resonance imaging-based morphometric measures in iNPH were used for correlation analyses between the magnitude of binding of these in vivo markers and clinical severity of the patients. Analysis of variance showed significant reduction in [11C]raclopride binding in the putamen and nucleus accumbens (P<0.05, corrected for multiple comparison) and unchanged striatal [11C]CFT binding in iNPH. The dorsal putamen [11C]raclopride binding correlated negatively with gait severity (r=0.720, P<0.05), and the nucleus accumbens [11C]raclopride binding correlated positively with emotional recognition score (r=0.727, P<0.05) in the disease group. No significant relationship was observed between BPs and morphometric measures. The current result of the postsynaptic D2 receptor reduction along with preserved presynaptic activity in the nigrostriatal dopaminergic system reflects a pathophysiology of iNPH. Postsynaptic D2 receptor hypoactivity in the dorsal putamen may predict the severity of gait impairment in iNPH. 相似文献
9.
Structural determination of geometrical isomers of microcystins LR and RR from cyanobacteria by two-dimensional NMR spectroscopic techniques 总被引:6,自引:0,他引:6
K Harada K Ogawa K Matsuura H Murata M Suzuki M F Watanabe Y Itezono N Nakayama 《Chemical research in toxicology》1990,3(5):473-481
A nondestructive method using a combination of three 2D NMR techniques, DQF-COSY (double quantum filter correlation spectroscopy), HMQC (1H-detected multiple quantum coherence), and HMBC (heteronuclear multiple bond correlation), were developed for structural determination of microcystins, toxic heptapeptides produced by cyanobacteria. With this procedure we were able to assign all carbons and protons of microcystins LR (1) and RR (2), thus determining the constituent amino acid sequences. The procedure was also applied to the microcystin-associated nontoxic minor components, which have molecular weights and amino acid compositions similar to those of 1 and 2 and toxicities different from those of 1 and 2. From detailed analysis of these spectra we rapidly deduced that the minor components are geometrical isomers with respect to C-7 of the diene in Adda of the parent toxins. The structures were finally confirmed to be 3 and 4 by ROESY (rotating frame nuclear Overhauser and exchange spectroscopy) technique. 相似文献
10.
Yasuhisa Fujibayashi Hideyuki Taniuchi Kouichi Wada Yoshiharu Yonekura Junji Konishi Akira Yokoyama 《Annals of nuclear medicine》1995,9(1):1-5
The reductive retention of62Cu-PTSM was comparatively studied in the brain and Ehrlich ascites tumor cells by electron spin resonance spectrometry and nonradioactive Cu-PTSM. In the brain, only the mitochondrial fraction showed the ability to reduce Cu-PTSM, and the other subcellular fractions did not. In contrast, the cytosolic fraction of Ehrlich ascites tumor cells was the specific site of Cu-PTSM reduction. It was therefore considered that the retention of Cu-PTSM in the brain is closely related to mitochondrial reduction, most probably involving the mitochondrial electron transport system. 相似文献