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11.
Summary The actin-activated ATPase activityPhysarum myosin was shown to be inhibited of M levels of Ca2+. To determine if Ca2+ regulates ATP-dependent movement ofPhysarum myosin on actin, latex beads coated withPhysarum myosin were introduced intoChara cells by intracellular perfusion. In perfusion solution containing EGTA, the beads moved along the parallel arrays ofChara actin filaments at a rate of 1.0–1.8 m/sec; however, in perfusion solution containing Ca2+, the rate reduced to 0.0–0.7 m/sec. The movement of beads coated with scallop myosin, whose actin-activated ATPase activity is activated by Ca2+, was observed only in the perfusion solution containing Ca2+, indicating that myosin is responsible for the inhibitory effect of Ca2+ onPhysarum myosin movement. The involvement of this myosin-linked regulation in the inhibitory effect of Ca2+ on the cytoplasmic streaming observed inChara internodal cell andPhysarum plasmodium was discussed.Abbreviations ATP
adenosine 5-triphosphate
- DTT
dithiothreitol
- EDTA
ethylenediaminetetraacetic acid
- EGTA
ethyleneglycolbis(-aminoethylether) N,N,N,N-tetraacetic acid
- PIPES
piperazine-N,N-bis(2-ethanesulfonic acid) 相似文献
12.
Hideya Hayashi Seiji Ito Teruo Tanaka Manabu Negishi Hideo Kawabe Yokohama Hiromitsu Kikuko Watanabe Osamu Hayaishi 《Prostaglandins & other lipid mediators》1987,33(4)
In view of the recent finding that prostaglandin D2 is stereospecifically converted to 9α,11β-prostaglandin F2, an isomer of prostaglandin F2α, a highly specific and sensitive radioimmunoassay for 9α,11β-prostaglandin F2 was developed and applied to determine the content of this prostaglandin in various rat tissues. Antisera against 9α-11β-prostaglandin F2 were raised in rabbits immunized with the bovine serum albumin conjugate, and [3H]9α,11β-prostaglandin F2 was enzymatically prepared from [3H]prostaglandin D2. The assay detected 9α,11β-prostaglandin F2 over the range of 20 pg to 1 ng, and the antiserum showed less than 0.04% cross-section with prostaglandin F2α, prostaglandin F2β and 9β,11β-prostaglandin F2. To avoid postmortem changes, tissues were frozen in liquid nitrogen immediately after removal. The basal level of 9α,11β-prostaglandin F2 was hardly detectable in various tissues of the rat examined, including spleen, lung, liver and brain; although it was found to be 0.31 ± 0.06 ng/g wet weight in the small intestine. During convulsion induced by pentylenetetrazole, enormous amounts of prostaglandin D2 (ca. 180 ng/g wet weight) and prostaglandin F2α (ca. 70 ng/g) were produced in the brain; however, 9α,11β-prostaglandin F2 was detected neither there nor in the blood. This result demonstrates that the conversion to 9α,11β-prostaglandin F2 is a minor pathway, if one at all, of prostaglandin D2 metabolism in the rat brain. 相似文献
13.
Isopropylidenation of lactose with 2,2-dimethoxypropane in the presence ofp-toluenesulfonic acid gave two products, which were identified by1H- and13C-NMR as 2,35,63,4-tri-O-isopropylidenelactose dimethyl acetal (1) and its 6-O-(2-methoxy)-isopropyl derivative (2). These products were used for the synthesis of 2-O-methyllactose (7), 2,6-di-O-methyllactose (9) and 2-O-benzyllactose (13). 相似文献
14.
A combined system of chemiluminescence detection and high performance liquid chromatography (CL–HPLC) was developed to determine primary peroxidation products in biological tissues, such as phosphatidylcholine hydroperoxide (PCOOH). The CL–HPLC assay consists of separation of lipid classes with HPLC and detection of hydroperoxide-specific chemiluminescence. Hydroperoxides react with heme compounds to produce oxidants as suggested by our early studies on tissue low-level chemiluminescence in which singlet molecular oxygen is generated as one of the excited species in several biological systems involving free radical events. In the CL–HPLC method, a cytochrome c–luminol mixture was used as a hydroperoxide-specific luminescent reagent, and the quantification of hydroperoxide was performed by detecting chemiluminescence due to the luminol oxidation caused by the oxidant produced during the lipid hydroperoxides with heme. The detection limit of PCOOH was 10 pmole hydroperoxide–O2. PCOOH in normal human blood was found to be 10–500 pmol/ml plasma and significantly higher levels of PCOOH were observed in some hospitalized patients. 相似文献
15.
Summary We have devised a method whereby any mutagenized cloned DNA from Bacillus subtilis can be reinserted at the original site on the B. subtilis chromosome. The procedure depends on the accuracy and high frequency of homologous recombination between the B. subtilis chromosome and the DNA taken up by the cell. The method makes use of two drug resistance selection markers (the chloramphenicol resistance gene and the neomycin resistance gene) and a marker gene which functions as a catalyst. The utility of the method has been demonstrated using leuB and pro of B. subtilis as target gene and catalyst, respectively, and mutations such as leuB: : cat, leuB
–, and pro: : neo constructed in vitro on the cloned DNA fragments. Transformation in sequential steps as (leuB
+ pro+)(leuB: : cat pro
+) (leuB
–
pro: : neo)(leuB
–
pro
+) resulted in a leuB
– single mutant without affecting other regions of the B. subtilis chromosome (gene-directed mutagenesis). We also demonstrate that other single mutations such as metD
– and pro
–, as well as the double mutation leuB
–
pro
– can be introduced by the same procedure. In principle, true isogenies with multiple mutations can be constructed by the method described in this paper. Furthermore, the procedure should be generally applicable to any organisms in which homologous recombination is proficient. 相似文献
16.
Tomokazu Indoh Sachiko Shirakawa Tohru Kubota Teruo Yashiki Emiko Isogai Nobuhiro Fujii 《Microbiology and immunology》1996,40(9):675-679
Persistent infections with mumps virus were established in several human lymphoid cells of T-cell origin (Molt-4, TALL-1, and CCRF-CEM) and human monocyte cells (U937 and THP-1). 2′,5′-Oligoadenylate synthetase (2–5AS) activity was demonstrated to be only slightly induced by interferon (IFN) or TPA (12-O-tetradecanoyl-phorbol-13-acetate) treatment in these cells. Treatment of the persistently infected cells with IFN or TPA did not stimulate an increase in the amount of synthetase mRNA. Induction of cell differentiation and augmentation of IFN production by TPA were demonstrated in U937 cells persistently infected with mumps virus (U937-MP). Similar results for IFN production were obtained from differentiated U937 cells. It is suggested that cell differentiation of U937 cells might be associated with the development of IFN inducibility. 相似文献
17.
18.
Studies on Mechano-Perception in Characean Cells: Development of a Monitoring Apparatus 总被引:3,自引:0,他引:3
An apparatus to monitor the electrical signal generated in Characells upon mechanical stimulation was developed. An internodalcell was stimulated by dropping a glass tubing with the intensityof the stimulus being controlled by changing either the weightof the glass tubing or the height from which it was dropped.Upon stimulation, a receptor potential was generated with theamplitude being dependent on the stimulus intensity. When thereceptor potential reached a threshold value, an action potentialwas generated. The receptor potential and action potential werecharacterized. The usefulness of this apparatus for analyzingreceptor potentials is discussed. (Received January 29, 1996; Accepted April 16, 1996) 相似文献
19.
Stabilization of the phosphorylated form of Bacillus subtilis DegU caused by degU9 mutation 总被引:1,自引:0,他引:1
Abstract A Bacillus subtilis response regulator, DegU9, carrying an amino acid alteration caused by the degU9 (Hy) mutation was partially purified, and phosphorylation and dephosphorylation of the protein was studied. The extent of phosphorylation was not as high as the level attained with wild-type DegU, but the DegU9-phosphate once formed was more stable than the wild-type DegU-phosphate. An in vivo study with a degU9 mutant showed that degS was necessary for the overproduction of exoproteases. These results suggest that phosphorylation is necessary for the mutant DegU9 to exert its effect and that the higher stability of phosphorylated DegU9 is responsible for the overproulation phenotype. 相似文献
20.
Safak Yalcin Hirohiko Kuratsune Koji Yamaguchi Teruo Kitani Koichi Yamanishi 《Microbiology and immunology》1994,38(7):587-590
Peripheral blood mononuclear cells collected from 13 patients with chronic fatigue syndrome and 13 healthy controls were analyzed for the presence of human herpesvirus 6 (HHV-6) DNA by variant-specific polymerase chain reaction and dot blot hybridization. HHV-6 DNA was detected in 7 of 13 (53%) patients, and of those 7 patients, 4 were positive for HHV-6 variant A DNA and 3 were for variant B. No HHV-6 DNA was detected in the controls. Serum antibody titers to the late antigen and antibody prevalence to the early antigen of HHV-6 were significantly higher in the patient group. These results suggest active replication of HHV-6 in patients with chronic fatigue syndrome. 相似文献