全文获取类型
收费全文 | 665篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
702篇 |
出版年
2021年 | 3篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 24篇 |
2014年 | 11篇 |
2013年 | 46篇 |
2012年 | 29篇 |
2011年 | 23篇 |
2010年 | 18篇 |
2009年 | 22篇 |
2008年 | 27篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 36篇 |
2004年 | 41篇 |
2003年 | 30篇 |
2002年 | 22篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 20篇 |
1998年 | 15篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 23篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1973年 | 7篇 |
1965年 | 2篇 |
1963年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
1.
Human skeletal muscle contains two major aminopeptidases: an anion-activated aminopeptidase B and an aminopeptidase M-like enzyme 总被引:1,自引:0,他引:1
S Ishiura T Yamamoto M Yamamoto M Nojima T Aoyagi H Sugita 《Journal of biochemistry》1987,102(5):1023-1031
Two major aminopeptidases, an aminopeptidase B and an aminopeptidase M-like enzyme, were purified from human skeletal muscle by DEAE-cellulose, HPLC gel filtration, and hydroxyapatite column chromatographies. The purified aminopeptidase B exhibits a molecular weight of 76,000 under both native and denaturing conditions. The activity of the aminopeptidase B is regulated by C1 ions and other anions in vitro. On the other hand, the aminopeptidase M-like enzyme is a monomeric protein having a molecular weight of 96,000. It is capable of significantly cleaving Phe-, Leu-, Arg-, and Ala-aminoacyl bonds in the presence of 2-mercaptoethanol. The pH optima for both enzymes are around 7.0, and bestatin is an effective inhibitor of both enzymes. 相似文献
2.
The distribution of the pulmonary artery and vein of the orangutan lung was examined. The right pulmonary artery runs obliquely
across the ventral side of the right bronchus at the caudally to the right upper lobe bronchiole. It then runs across the
dorsal side of the right middle lobe bronchiole. Thereafter it runs obliquely across the dorsal side of the right bronchus,
and then along the dorso-medial side of the right bronchus. This course is different from that in other mammals. During its
course, it gives off branches which run mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery
runs across the dorsal side of the left middle lobe bronchiole, then along the dorso-lateral side of the left bronchus, giving
off branches which run along each bronchiole. The pulmonary veins run mainly the ventral or medial side of, along or between
the bronchioles. In the left lung, the left middle lobe vein has two trunks; one enters the left atrium, and the other enters
the left lower lobe pulmonary venous trunk. This is also different from that found in most mammals. Finally, the pulmonary
veins enter the left atrium with four large veins. 相似文献
3.
A high-molecular-mass protease, ingensin, was purified to homogeneity from rabbit reticulocytes by DEAE-cellulose, HPLC gel filtration, and hydroxyapatite chromatographies. By these procedures, ingensin activity was separated from the activities of two other unique aminopeptidases, one of which is activated by ATP. Ingensin had the following properties: the optimum activity was seen around pH 9.0 and at 50 degrees C; addition of 0.04% SDS and 1 mg/ml linoleic acid resulted in 8- and 4-fold increases in peptide-hydrolyzing activity, respectively. The molecular mass was found to be 700,000 +/- 100,000 daltons on gel filtration, but SDS electrophoresis revealed that the enzyme is composed of several subunits with molecular weights of less than 35,000. The N-terminal-blocked tyrosine- and arginine-MCA derivatives, but not Arg-MCA, were hydrolyzed rapidly by ingensin. The approximate Km values for the reaction of ingensin with Suc-Leu-Leu-Val-Tyr-MCA and Z-Ala-Arg-Arg-MCA were 0.32 and 0.12 mM, respectively. The degradation of several proteins in the reticulocyte extract was stimulated by the addition of SDS and linoleic acid. The activator concentrations necessary for stimulation of the protein hydrolysis are similar to those of the purified reticulocyte ingensin for synthetic substrates. Ingensin did not associate with either right-side-out or inside-out red cell membranes. These results suggest that ingensin is a cytosolic fatty acid-stimulated protease, which is involved in the protein turnover in reticulocyte extracts. 相似文献
4.
Degradation of Dehydrodivanillin by Anaerobic Bacteria from Cow Rumen Fluid 总被引:7,自引:7,他引:0 下载免费PDF全文
Dehydrodivanillin (DDV; 0.15 g/liter) was biodegradable at 37°C under strictly anaerobic conditions by microflora from cow rumen fluid to the extent of 25% within 2 days in a yeast extract medium. The anaerobes were acclimated on DDV for 2 weeks, leading to DDV-degrading microflora with rates of degradation eight times higher than those initially. Dehydrodivanillic acid and vanillic acid were detected in an ethylacetate extract of a DDV-enriched culture broth by thin-layer, gas, and high-performance liquid chromatographies and by mass spectrometry. 相似文献
5.
6.
7.
Recombinational hotspot specific to female meiosis in the mouse major histocompatibility complex 总被引:13,自引:0,他引:13
Toshihiko Shiroishi Naoto Hanzawa Tomoko Sagai Masahiro Ishiura Takashi Gojobori Michael Steinmetz Kazuo Moriwaki 《Immunogenetics》1990,31(2):79-88
Thewm7 haplotype of the major histocompatibility complex (MHC), derived from the Japanese wild mouseMus musculus molossinus, enhances recombination specific to female meiosis in theK/A
interval of the MHC. We have mapped crossover points of fifteen independent recombinants from genetic crosses of thewm7 and laboratory haplotypes. Most of them were confined to a short segment of approximately 1 kilobase (kb) of DNA between theA
3 andA
2 genes, indicating the presence of a female-specific recombinational hotspot. Its location overlaps with a sex-independent hotspot previously identified in theMus musculus castaneus CAS3 haplotype. We have cloned and sequenced DNA fragments surrounding the hotspot from thewm7 haplotype and the corresponding regions from the hotspot-negative B10.A and C57BL/10 strains. There is no significant difference between the sequences of these three strains, or between these and the published sequences of the CAS3 and C57BL/6 strains. However, a comparison of this A3/A2 hotspot with a previously characterized hotspot in theE gene revealed that they have a very similar molecular organization. Each hotspot consists of two elements, the consensus sequence of the mouse middle repetitive MT family and the tetrameric repeated sequences, which are separated by 1 kb of DNA.The nucleotide sequence data reported in this paper have been submitted to the DNA Data Bank of Japan nucleotide sequence database and have been assigned the accession numbers d90007-9.
Offprint requests to: T. Shiroishi. 相似文献
8.
The lungs of three silvered lutongs (Presbytis cristata) were examined. The right and left lungs have the dorsal, lateral, ventral, and medial bronchiole systems, which arise from
the corresponding sides of both bronchi, respectively. Bronchioles in the dorsal and lateral bronchiole systems are well developed,
whereas those in the ventral and medial bronchiole systems are poorly developed and lack some portions. According to the fundamental
structure of bronchial ramifications of the mammalian lung (Nakakuki, 1975, 1980), the right lung consists of the upper, middle, lower, and accessory lobes, whereas the left lung consists of
a bilobed middle lobe and a lower lobe, in which the right upper lobe is extremely well developed. The right pulmonary artery
runs across the ventral side of the right upper lobe bronchiole, and then across the dorsal side of the right middle lobe
bronchiole. Initially it runs along the lateral side of the right bronchus and then gradually comes to run along the dorsal
side. During its course, it gives off branches which run mainly along the dorsal or lateral side of the bronchiole. The left
pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, and then follows the same course as that
in the right lower lobe. The pulmonary veins run medially or ventrally to the bronchioles, and finally enter the left atrium
as four or five large veins. 相似文献
9.
Takaharu Ishibashi Mikio Nakazawa Shoichi Imai 《Molecular and cellular biochemistry》1993,119(1-2):109-120
Using31P-,23Na- and39K-NMR, we assessed ischemic changes in high energy phosphates and ion contents of isolated perfused rat hearts continuously and systematically. To discriminate intra- and extracellular Na+, a shift reagent (Dy(TTHA)3–) was used in23Na-NMR study. In39K-NMR study, the extracellular K+ signal was suppressed by inversion recovery pulse sequence in order to obtain intracellular K+ signal without using shift reagnets. During the early period of ischemia, increases in intracellular Na+ and inorganic phosphate (Pi) were observed in addition to the well-documented decreases in creatine phosphate and ATP and a fall of intracellular pH, suggesting an augmented operation of Na+–H+ exchange triggered by a fall of the intracellular pH resulted from breakdown of ATP. At around 15 min of ischemia, a second larger increase in intracellular Na+ and a decrease in intracellular K+ were observed in association with a second increase in Pi. This was accompnanied by an abrupt rise of the ventricular end-diastolic pressure. As there was a depletion of ATP at this time, the increase in intracellular Na+ and associated decrease in intracellular K+ may be explained by inhibition of the Na+–K+ ATPase due to the depletion of ATP. A longer observation with31P-NMR revealed a second phosphate peak (at lower magnetic field to ordinary Pi peak) which increased its intensity as ischemic time lengthened. The pH of this 2nd peak changed in parallel with the changes in pH of the bathing solution, indicating the appearance of a compartment whose hydrogen concentration is in equilibrium with that of the external compartment. Thus, the peak could be used as an index of irreversible membrane damage of the myocardium. 相似文献
10.
Yoshio Oka Tetsuro Kobayashi Shoichi Fujita Nariaki Matsuura Shigeru Okamoto Hideki Asakawa Atsuo Murata Takesada Mori 《In vitro cellular & developmental biology. Animal》1993,29(7):537-542
Summary A human anaplastic thyroid cancer cell line K-119, derived from a 77-yr-old woman who had developed marked neutrophilia and
underwent surgery for anaplastic thyroid cancer, has been established. The spindlelike and polygonal cells in shape are stably
proliferating since the beginning of its culture 2 yr ago. The cells grow rapidly and the population doubling time is 26 h.
The chromosomes show many abnormalities and many marker chromosomes have been observed. Heterotransplantation of the cells
into nude mice has resulted in the formation of tumors that are histologically interpreted as anaplastic cancer. The most
noteworthy characteristics of the cell line are the many Ki-67-positive cells (86.3%) and that the cell line spontaneously
secretes granulocyte colony-stimulating factor (G-CSF) and releases increased amounts of G-CSF in response to the stimulation
of tumor necrosis factor, interleukin 1α, and interleukin 1β. The conditioned medium obtained from K-119 cells contains an
autocrine factor stimulating the proliferation of themselves. 相似文献