全文获取类型
收费全文 | 36228篇 |
免费 | 1627篇 |
国内免费 | 298篇 |
专业分类
耳鼻咽喉 | 275篇 |
儿科学 | 669篇 |
妇产科学 | 421篇 |
基础医学 | 4798篇 |
口腔科学 | 1006篇 |
临床医学 | 2112篇 |
内科学 | 9045篇 |
皮肤病学 | 857篇 |
神经病学 | 2449篇 |
特种医学 | 1253篇 |
外科学 | 6456篇 |
综合类 | 145篇 |
一般理论 | 1篇 |
预防医学 | 1007篇 |
眼科学 | 630篇 |
药学 | 2094篇 |
中国医学 | 124篇 |
肿瘤学 | 4811篇 |
出版年
2024年 | 25篇 |
2023年 | 204篇 |
2022年 | 542篇 |
2021年 | 888篇 |
2020年 | 456篇 |
2019年 | 654篇 |
2018年 | 851篇 |
2017年 | 660篇 |
2016年 | 781篇 |
2015年 | 805篇 |
2014年 | 1085篇 |
2013年 | 1381篇 |
2012年 | 2247篇 |
2011年 | 2619篇 |
2010年 | 1483篇 |
2009年 | 1217篇 |
2008年 | 2241篇 |
2007年 | 2471篇 |
2006年 | 2312篇 |
2005年 | 2496篇 |
2004年 | 2400篇 |
2003年 | 2398篇 |
2002年 | 2406篇 |
2001年 | 359篇 |
2000年 | 302篇 |
1999年 | 432篇 |
1998年 | 577篇 |
1997年 | 455篇 |
1996年 | 434篇 |
1995年 | 371篇 |
1994年 | 323篇 |
1993年 | 297篇 |
1992年 | 212篇 |
1991年 | 189篇 |
1990年 | 187篇 |
1989年 | 172篇 |
1988年 | 151篇 |
1987年 | 114篇 |
1986年 | 104篇 |
1985年 | 93篇 |
1984年 | 105篇 |
1983年 | 85篇 |
1982年 | 71篇 |
1981年 | 87篇 |
1980年 | 83篇 |
1979年 | 61篇 |
1978年 | 41篇 |
1977年 | 32篇 |
1976年 | 24篇 |
1973年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Hayashi T Kawakami M Sasaki S Katsumata T Mori H Yoshida H Nakahari T 《Experimental physiology》2005,90(4):535-544
Ciliary beat frequency (CBF) was measured by video-optical microscopy in rat tracheal and distal airway ciliary cells using a slice preparation. In tracheal ciliary cells (tracheal slice), ATP or 2-methylthio ATP (MeSATP) increased CBF, which was inhibited by suramin (100 microm, an inhibitor of purinergic receptor). Ionomycin (5 microm) or thapsigargin (2 microm) increased CBF similarly. Ca2+-free solution or addition of Ni2+ (1 mm) decreased CBF gradually by approximately 25% and subsequent stimulation with ATP (10 microm) increased CBF transiently. The purinergic agonist experiments demonstrated that ATP increases CBF in tracheal ciliary cells via both P2X and P2Y receptors. ATP increased the intracellular calcium concentration ([Ca2+]i) in tracheal ciliary cells. However, in distal airway ciliary cells (lung slice), ATP did not increase CBF and [Ca2+]i, although a Ca2+-free solution decreased CBF, and ionomycin (5 microm) or thapsigargin (2 microm) increased it. Moreover, acetylcholine (100 microm) did not increase CBF in distal airway ciliary cells, although it increased CBF in tracheal ciliary cells. Terbutaline (10 microm), a selective beta2-adrenergic agonist, increased CBF in both tracheal and distal airway ciliary cells. These observations suggest that the Ca2+-mobilization mechanisms via purinergic or muscarinic receptors of the distal airway ciliary cell may be different from those of the tracheal ciliary cell. In conclusion, the CBF increase is differently regulated in the tracheal and distal airway epithelia of the rat. 相似文献
102.
Hirokazu Taniguchi Kenjiro Hamamoto Takahiro Nagano Yuji Kishimoto Takashi Kimura Hideki Fujitake Kojiro Yasunaga 《Medical Electron Microscopy》1993,26(1):13-18
Ultrastructural myeloperoxidase (MPO) activity and myeloid-associated antigen (MyAg) expression were investigated in 12 adult
patients with acute lymphoblastic leukemia (ALL). Ultrastructural MPO was detected by 3 different methods. Immunophenotyping
was performed by flow cytometry, using a series of monoclonal antibodies. Ultrastructural MPO-positive blast cells were detected
in 6 patients (50%). In 5 of these 6 patients, the methods detecting both MPO and platelet peroxidase (PPO) activities found
MPO-positive blast cells more frequently than those detecting MPO activity alone. In 2 patients (17%), at least one kind of
MyAg was positive. Ultrastructural MPO activity was detected more frequently than MyAg expression in ALL patients. This method
of detecting PPO and MPO is recommended for detection of ultrastructural MPO-positive ALL. 相似文献
103.
Akagi M Inui K Nakajima S Shima M Nishigaki T Muramatsu T Kokubu C Tsukamoto H Sakai N Okada S 《Journal of human genetics》2000,45(1):60-62
Fanconi-Bickel syndrome (FBS), or glycogen storage disease type XI, is a rare autosomal recessive disorder characterized
by hepatorenal glycogen accumulation, Fanconi nephropathy, and impaired utilization of glucose and galactose. Recently, this
disease was elucidated to link mutations in the glucose transporter 2 (GLUT2) gene. Only three mutations in three FBS families have been reported. Therefore, it is important to elucidate mutations in
the GLUT2 gene in FBS by answering the question of whether the syndrome is a single gene disease. In this report, we describe two patients
in two unrelated families clinically diagnosed with FBS. No mutation in the entire protein coding region of the GLUT2 gene was detected in patient 1, which suggested that no mutation existed in the GLUT 2 gene, or that some mutations had affected the expression of the GLUT 2 gene. In patient 2, a novel homozygous nonsense mutation (W420X, Trp at codon 420 to stop codon) was detected. These results
support the correlation between GLTU2 gene mutation and FBS syndrome. However, many patients must be analyzed to determine whether other genes are involved in
FBS.
Received: July 16, 1999 / Accepted: September 3, 1999 相似文献
104.
Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II. 相似文献
105.
Takashi Hirano Shinichi Ohashi Satoshi Morimoto Keishiro Tsuda Tomowo Kobayashi Shigeru Tsukagoshi 《Macromolecular chemistry and physics.》1986,187(12):2815-2824
Polymeric conjugates of adriamycin (ADR) ( 2 ) or daunomycin (DM) ( 3 ) were synthesized by reaction of the drugs with the copolymer of divinyl ether and maleic anyhdride (DIVEMA) ( 1 ). The content of ADR moieties in the DIVEMA conjugate ( 4 ) could be varied depending on the reaction conditions up to 35,8 wt.-%. Considering the low toxicity and the high possibility of renal excretion, DIVEMA with M?w of 7000 and M?w/M?n = 1,6 was used for the conjugation. The rate of drug release from the conjugate was determined under physiological conditions by reversed phase HPLC. Within 14 days only 15% of the attached ADR was released from conjugate 4 . The antitumor activity of the conjugates was tested in vitro and in vivo against mouse P388 leukemia. Conjugate 4 proved to be 28 times less active than ADR in vitro, which could be explained from the slow drug-release. On the contrary 50% of the leukemic mice treated by 4 survived more than 60 days, whereas no mice given ADR alone or the admixture of ADR and DIVEMA survived 30 days. An antitumor activity of the polymeric conjugate better than that of the free drug was also observed in vivo with DM. Such a polymeric effect can be attributed either to the change in body distribution, the difference in pharmacokinetics, or the slow drugrelease. 相似文献
106.
Takashi Wakabayashi Michio Horiuchi Sachiyo Kawamoto Hiroyuki Onda 《Pathology international》1984,34(3):481-488
Ultrastructure of megamitochondria in mouse hepatocytes induced by cuprizone was analyzed in the light of the fusion of inner mitochondrial membranes. Hepatic parenchymal cells of mice fed with a 0.5% cuprizone-diet for 7–8 days were characterized by megamitochondria with numerous cristae including disoriented, shorter ones than those of the control and those in vesicular configuration. After feeding the animals with cuprizone for 15–16 days, megamitochondria increased their sizes further and the number of cristae decreased drastically. Numbers of cristae based on a unit-mitochondrial area were 41.3$pL10.8 for the former type of cristae-enriched megamitochondria and 3.8 $pL 1.8 for the latter type of megamitochondria with the value of 23.9 $pL 6.2 for the control. Considering the content of cytochromes in megamitochondria previously reported, these results might suggest that the fusion and defusion of inner mitochondrial membrane take place along with the fusion of outer membranes during the megamitochondrial formation. ACTA PATHOL. JPN. 34: 481–488, 1984. 相似文献
107.
Takashi Hirano Shohei Inoue Teiji Tsuruta 《Macromolecular chemistry and physics.》1975,176(7):1913-1917
The stereochemistry of the copolymerization of optically active phenylepoxyethane ( 5 ) with carbon dioxide using a diethylzinc/water system as catalyst was investigated. The optically active copolymer, poly(oxycarbonyloxy-2-phenylethylene) ( 1 ), was hydrolyzed and the oxy-2-phenylethylene unit was isolated in the form of 1,2-bis(trimethylsilyloxy)-1-phenylethane ( 3 ). The determination of the optical activity of this ether led to the conclusion that the ring opening of 5 takes place predominantly at the methineoxygen linkage accompanying an inversion in the copolymerization. This fact is in sharp contrast with the stereochemistry of the copolymerization of carbon dioxide with 1,2-epoxypropane in which the ring opening takes place at the methylene-oxygen linkage. 相似文献
108.
Huh WK Oono T Shirafuji Y Akiyama H Arata J Sakaguchi M Huh NH Iwatsuki K 《Journal of molecular medicine (Berlin, Germany)》2002,80(10):678-684
Defensins are cationic antimicrobial peptides with a broad spectrum. Recently human beta-defensin 2 (hBD-2) has been isolated from psoriatic skin; however, its exact localization and fate have not been fully understood. We studied the distribution pattern of hBD-2 in skin tissues of psoriasis and other inflammatory skin diseases. In the upper spinous and granular layer of psoriasis vulgaris hBD-2 was present in the cytoplasm. In the horny layer the positive signals were in a basket-weave pattern, indicating possible accumulation of hBD-2 in the intercellular space. The similar pattern of hBD-2 distribution was observed in the lesions of nummular eczema and atopic dermatitis. hBD-2 was not detected in the section of normal elbow and knee skin. When isolated psoriatic scales were stained, hBD-2 was detected in a wrapping paper-like distribution pattern surrounding the corneocytes. In horny layer of psoriatic skin hBD-2 was closely associated or colocalized with elafin, which is known to be in extracellular space, as demonstrated by double staining. Western blot analysis using cultured human keratinocytes detected hBD-2 with an expected size in the conditioned medium and in the cell lysates when stimulated with 5% FCS or IL-alpha. These results indicate that hBD-2 was synthesized and remained in cytoplasm in the upper spinous and granular layer, and then secreted into intercellular space in the horny layer. This dynamic change in hBD-2 distribution in epidermis is certainly relevant to function as an innate host defense mechanism against invading micro-organisms. 相似文献
109.
Shigeo Aizawa Masafumi Suzuki Yasushi Kikuchi Takashi Nikaido Kenji Matsumoto 《Pathology international》1987,37(7):947-954
Seven metastasizing small renal cell carcinomas smaller than 30 mm in the greatest diameter were clinicopathologically studied for a better understanding of their characteristic features as compared to those of small tumors without metastases. Grayish-white infiltrating tumors in gross appearance and alveolar or solid microscopic structure consisting of granular or spindle cells and of atypical nuclei were suggestive of having metastases. Two tumors which had positive reactions to the lower nephron markers such as SB A, PNA, and/or DBA were considered to be of lower nephron origin and displayed poor prognosis. ACTA PATHOL. JPN. 37: 947–954, 1987. 相似文献
110.
Noriyuki Sato Takashi Minase Yutaka Yoshida Eimei Narimatsu Kohzo Muroya Kazuaki Asaishi Kokichi Kikuchi 《Pathology international》1984,34(6):1355-1363
A rare case of extraskeletal mesenchymal chondrosarcoma in a 47-year-old woman is reported. The tumor was located in the soft tissue of left upper arm without any involvement of the humerus. The outer portion of the tumor was histologically composed of primitive mesenchymal cells, and the inner portion showed zones of cartilaginous differentiation. Ultrastructurally, the tumor cells in the primitive areas had a relatively small number of mitochondria, rough endoplasmic reticulum, and free polysomes, and the matrix of the tumor consisted of dense bundles of collagen fibrils. The cartilaginous cells seen in the central portion of tumor were embedded in the matrix of abundant collagen fibrils and matrix granules. They had polysomes, well-developed Golgi complexes, and ample rough endoplasmic reticulum frequently with dilatation. Clear zones adjacent to the cells were seen in the extracellular matrix. With a review of the literature, the histogenesis of this particular tumor is discussed. ACTA PATHOL. JPN. 34: 1355–1363, 1984. 相似文献