全文获取类型
收费全文 | 14784篇 |
免费 | 647篇 |
国内免费 | 64篇 |
专业分类
耳鼻咽喉 | 190篇 |
儿科学 | 329篇 |
妇产科学 | 156篇 |
基础医学 | 1798篇 |
口腔科学 | 520篇 |
临床医学 | 873篇 |
内科学 | 3296篇 |
皮肤病学 | 300篇 |
神经病学 | 1137篇 |
特种医学 | 664篇 |
外科学 | 2776篇 |
综合类 | 52篇 |
一般理论 | 1篇 |
预防医学 | 314篇 |
眼科学 | 258篇 |
药学 | 895篇 |
中国医学 | 23篇 |
肿瘤学 | 1913篇 |
出版年
2023年 | 61篇 |
2022年 | 125篇 |
2021年 | 209篇 |
2020年 | 109篇 |
2019年 | 189篇 |
2018年 | 249篇 |
2017年 | 216篇 |
2016年 | 270篇 |
2015年 | 257篇 |
2014年 | 380篇 |
2013年 | 454篇 |
2012年 | 721篇 |
2011年 | 841篇 |
2010年 | 513篇 |
2009年 | 488篇 |
2008年 | 760篇 |
2007年 | 821篇 |
2006年 | 822篇 |
2005年 | 828篇 |
2004年 | 861篇 |
2003年 | 794篇 |
2002年 | 773篇 |
2001年 | 282篇 |
2000年 | 324篇 |
1999年 | 337篇 |
1998年 | 236篇 |
1997年 | 226篇 |
1996年 | 209篇 |
1995年 | 164篇 |
1994年 | 175篇 |
1993年 | 169篇 |
1992年 | 237篇 |
1991年 | 207篇 |
1990年 | 211篇 |
1989年 | 236篇 |
1988年 | 197篇 |
1987年 | 187篇 |
1986年 | 172篇 |
1985年 | 136篇 |
1984年 | 116篇 |
1983年 | 111篇 |
1982年 | 68篇 |
1981年 | 62篇 |
1980年 | 57篇 |
1979年 | 78篇 |
1978年 | 72篇 |
1977年 | 58篇 |
1974年 | 44篇 |
1972年 | 50篇 |
1971年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
T Baba T Ochiya K Yamaguchi A Baba T Takase K Uyeno 《Clinical immunology and immunopathology》1986,39(1):24-36
Sarcoidosis sera were found to have the ability to induce normal human monocytes to spread. Gel filtration of sarcoidosis sera on Sephadex G-200 showed that the factor mainly responsible for this activity had a molecular weight of about 70,000. The spreading factor also possessed the ability to increase all cell size of normal human monocytes as well as to increase their phagocytosis and glucose consumption. Accordingly, the spreading factor seems to be considered as a monocyte activating factor. Sarcoidosis sera showed a macrophage migration inhibitory activity, as well. On Sephadex G-200 column chromatography of the sera, the most obvious inhibitory activity was eluted in the fraction with a molecular weight of about 45,000. The macrophage migration inhibitory factor had the ability neither to increase cell size of normal human monocytes nor to increase their phagocytosis and glucose consumption. 相似文献
92.
Yasuhiko Hirata Hiromi Ishibashi Harumichi Kimura Kazuhiro Hayashida Masanori Nagano Hideo Okubo 《Inflammation》1985,9(2):201-209
Isolated rat Kupffer cells produced a factor which stimulated the synthesis of
2-macroglobulin (2M) in primary cultured rat hepatocytes. Although Kupffer cells placed in culture produced the factor without stimulation by lipopolysaccharide (LPS), the LPS-stimulated cells produced larger amounts of the factor. On the other hand, the production of the factor was inhibited by addition of actinomycin D. The induction of2M synthesis by cultured hepatocytes was enhanced in the presence of dexamethasone (Dex), in that hepatic synthesis of2M increased by addition of the factor alone and with Dex 1.5 and three- to four-fold, respectively. The factor was nondialyzable and stable at 60°C for 30 min. When the factor was fractionated using the molecular sieve method, the activity recovered in the fraction had a molecular weight of over 30,000. 相似文献
93.
Hideo Hatanaka Kazuo Sugiyama Tadao Nakaya Minoru Imoto 《Macromolecular chemistry and physics.》1975,176(11):3231-3242
Photocrosslinkable polymers containing chalconecarbonyl units were prepared. 2-Methacryloyloxyethyl 4-chalconecarboxylate ( 1 ) and 2-methacryloyloxyethyl 4′chalconecarboxylate ( 2 ) were synthesized and polymerized by a radical initiator. 1 was copolymerized with methyl methacrylate. The properties of the resulting polymers as photosensitive resins are described. 相似文献
94.
Three-dimensional two-layer collagen matrix gel culture model for evaluating complex biological functions of monocyte-derived dendritic cells 总被引:4,自引:0,他引:4
Tasaki A Yamanaka N Kubo M Matsumoto K Kuroki H Nakamura K Nakahara C Onishi H Kuga H Baba E Tanaka M Morisaki T Katano M 《Journal of immunological methods》2004,287(1-2):79-90
Dendritic cell-like cells (Mo-DCs) generated from peripheral blood monocytes with interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been used as tools to treat cancer patients (DC-vaccines). Because Mo-DCs have multiple antigen presentation-related functions, including phagocytosis, migration, cytokine production, and T cell stimulation, establishment of a method for simultaneously evaluating the various functions of Mo-DCs is important. We developed a new in vitro three-dimensional two-layer collagen matrix culture model that consists of a collagen gel containing Mo-DCs as the lower layer and a collagen gel containing necrotic GCTM-1 tumor cells and/or T cells as the upper layer. We used this system to observe simultaneously multiple functions of Mo-DCs by phase-contrast or fluorescence microscopy and to assess IL-12 secretion during more than 2 weeks of culture. We also observed interactions between Mo-DCs and necrotic GCTM-1 or T cells on an individual cell basis by time-lapse videomicroscopy. In addition, we collected Mo-DCs from the collagen gels by collagenase treatment and analyzed the expression of antigen presentation-related molecules such as HLA-DR, CD80, CD83, and CD86 on Mo-DCs. This model may be a useful tool for evaluation of the various functions of Mo-DCs used as DC vaccines and for studies of the complex behaviors of Mo-DCs in vivo. 相似文献
95.
Role of KCNQ1 in the cell swelling-induced enhancement of the slowly activating delayed rectifier K(+) current 总被引:2,自引:0,他引:2
Kubota T Horie M Takano M Yoshida H Otani H Sasayama S 《The Japanese journal of physiology》2002,52(1):31-39
Cell swelling enhances a slowly activating delayed rectifier K(+) current (I(Ks)) in cardiac cells. This investigation was undertaken to determine which of the two structural units reconstituting the I(Ks) channel, KCNQ1 (KvLQT1) and KCNE1 (minK/IsK), plays a key role in the cell swelling-induced I(Ks) enhancement and to dissect a possible involvement of tyrosine phosphorylation therein. KCNQ1 was transiently expressed alone or together with KCNE1 in a heterologous mammalian cell line. Two distinct whole-cell membrane currents were separately observed during the exposure of transfected cells to various degrees of hyposmotic solutions. A hyposmotic challenge (0.7 times control osmolarity) resulted in about a twofold increase not only in the heteromeric KCNQ1/KCNE1, but also in the homomeric KCNQ1 channel currents. There was no significant difference in the incremental ratio of current amplitude in response to hyposmotic stress between the two KCNQ1-related currents, and the cells expressing the heteromeric channels swelled less than those with the homomeric channels or without the exogenous ones. The cell swelling-induced I(Ks) enhancement was not affected by a protein tyrosine kinase (PTK) inhibitor, by genistein (50 microM), or by an inhibitor of phosphotyrosine phosphatase (PTP), orthovanadate (500 microM), or a nonhydrolyzable ATP analogue, AMP-PNP (5 mM). Taken together, it is very likely that KCNQ1 might primarily participate in the I(Ks) enhancement by osmotic cell swelling. The obligatory dependence of the I(Ks) augmentation on PTK activity remained to be demonstrated, at least, in this expression system. 相似文献
96.
Harderian gland dependency of immunoglobulin A production in the lacrimal fluid of chicken 总被引:2,自引:0,他引:2 下载免费PDF全文
Involvement of the Harderian gland (HG) in the production of lacrimal immunoglobulin (especially IgA) was investigated. The lacrimal concentration of each immunoglobulin class was not affected by surgical bursectomy but was reduced by cyclophosphamide (CY) and testosterone (TP) treatments. Surgical removal of the Harderian gland caused a remarkable reduction of both the lacrimal concentration of each immunoglobulin class and the specific antibody titre, and and IgA was almost undetectable. The lacrimal concentration of each immunoglobulin class, as well as the specific antibody titre, was not affected by surgical removal of the Lacrimal gland (LG). The route of antigen administration produced no difference in the class of lacrimal immunoglobulin produced. The results indicate that the production of immunoglobulin in chicken tears may be dependent on the HG and that lacrimal immunoglobulin may be synthesized and secreted locally in the HG. Lymphocytes of the HG are of bursa of Fabricius origin and are seeded into the HG prior to hatching and its lymphocytes do not appear to be involved in systemic immunity. 相似文献
97.
A histological evaluation for guided bone regeneration induced by a collagenous membrane 总被引:5,自引:0,他引:5
Taguchi Y Amizuka N Nakadate M Ohnishi H Fujii N Oda K Nomura S Maeda T 《Biomaterials》2005,26(31):6158-6166
This study was designed to evaluate the histological changes during ossification and cellular events including osteogenic differentiation responding to collagenous bioresorbable membranes utilized for GBR. Standardized artificial bony defects were prepared at rat maxillae, and covered with a collagenous bioresorbable membrane. These animals were sacrificed at 1, 2, 3 and 4 weeks after the GBR-operation. The paraffin sections were subject to tartrate resistant acid phosphatase (TRAP) enzyme histochemistry and immunohistochemistry for alkaline phosphatase (ALP), osteopontin (OP) and osteocalcin (OC). In the first week of the experimental group, woven bone with ALP-positive osteoblasts occupied the lower half of the cavity. The collagenous membrane included numerous ALP-negative cells and OP-immunoreactive extracellular matrices. At 2 weeks, the ALP-, OP- and OC-immunoreactivity came to be recognizable in the region of collagenous membrane. Since ALP-negative soft tissue separated the collagenous membrane and the new bone originating from the cavity bottom, the collagenous membrane appeared to induce osteogenesis in situ. At 3 weeks, numerous collagen fibers of the membrane were embedded in the adjacent bone matrix. At 4 weeks, the membrane-associated and the cavity-derived bones had completely integrated, showing the same height of the periosteal ridge as the surrounding alveolar bones. The collagen fibers of a GBR-membrane appear to participate in osteogenic differentiation. 相似文献
98.
Shouji Iwatsuki Hideo Kasahara Yuya Yamashita 《Macromolecular chemistry and physics.》1967,104(1):254-262
RANEY metals (Ni, Fe, Co), URUSHIBARA metals (Ni, Co) and ULIMANN cu initiate the polymerization of methylmethacrylate. Diamines, diols or organic halides enhance their reactivity. In the presence of CCl4, the polymerization rate (Rp) is proportional to the square root of the amount of both metals and CCl4, and to the first power of the monomer concentration, but Rp becomes constant and independent of the concentration of CCl4 when there is a great excess of CCl4. We concluded that this polymerization follows the free radical mechanism and the participation of a zero-valent metal atom in the initiation reaction including complex formation between metal and CCL4 is suggested. 相似文献
99.
We develop a compact scanning head for use in laser confocal fluorescence microscopy for in situ fluorescence imaging of organs. The head, cylindrical in shape, has 3.5 mm diameter and 30 mm length, and is thus small enough to operate in a living rat heart. The lateral and axial resolutions, defined as full widths at half maximum (FWHM) of a point spread function (PSF), measures 1.0 and 5.0 microm, respectively, for 488-nm excitation and 1.0 and 5.4 microm, respectively, for 543-nm excitation. The chromatic aberration between 488- and 543-nm laser beams is well suppressed. We perform Ca2+ imaging in cardiomyocytes through the right ventricular chamber of a perfused rat heart in line-scan mode with 2.9-ms time resolution. We also carried out two-color imaging of a fixed mouse heart and liver with subcellular resolution. The compact head of the microscope equipped with a line-scan imaging mode and two-color imaging mode is useful for in situ imaging in living organs with subcellular resolution and can advantageously be applied to in vivo research. 相似文献
100.
By combining cell surface staining with fluorochrome-conjugated monoclonal antibodies and Hoechst 33342 dye supravital staining, Matsuzaki et al. have succeeded in enriching hematopoietic stem cells (HSCs) essentially to homogeneity. When single-cell transplantation analysis was performed using the isolated cells, over 95% of the recipient mice showed long-term multilineage engraftment. The work demonstrates unexpectedly high marrow seeding efficiency of HSCs and proposes high marrow homing capacity as a new criterion for HSCs. 相似文献